Fallback procedures when the path loss or spatial transmit quasi-collocation (qcl) reference from neighboring cells is failing for sounding reference signals (srs) for positioning

ABSTRACT

Disclosed are techniques for wireless communication. In an aspect, a UE receives a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating a downlink path loss or determining an uplink spatial transmit beam, determines that a first downlink reference signal received from the neighboring cell cannot be used for estimating the downlink path loss or determining the uplink spatial transmit beam, in response to the determination, estimating the downlink path loss or determining the uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or a serving cell, and transmits an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for patent is a continuation application of U.S.patent application Ser. No. 17/086,422, entitled “FALLBACK PROCEDURESWHEN THE PATH LOSS OR SPATIAL TRANSMIT QUASI-COLLOCATION (QCL) REFERENCEFROM NEIGHBORING CELLS IS FAILING FOR SOUNDING REFERENCE SIGNALS (SRS)FOR POSITIONING,” filed Nov. 1, 2020, which is a divisional applicationof U.S. patent application Ser. No. 16/876,851, entitled “FALLBACKPROCEDURES WHEN THE PATH LOSS OR SPATIAL TRANSMIT QUASI-COLLOCATION(QCL) REFERENCE FROM NEIGHBORING CELLS IS FAILING FOR SOUNDING REFERENCESIGNALS (SRS) FOR POSITIONING,” filed May 18, 2020, which claims thebenefit of U.S. Provisional Application No. 62/850,503, entitled“REPORTING OF INFORMATION RELATED TO SOUNDING REFERENCE SIGNALS (SRS)TIMING ADJUSTMENTS,” filed May 20, 2019, each assigned to the assigneehereof, and expressly incorporated herein by reference in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

Aspects of the disclosure relate generally to telecommunications, andmore particularly to the reporting of information related to uplinkreference signal timing adjustments for enhanced uplink reference signalprocessing.

2. Description of the Related Art

Wireless communication systems have developed through variousgenerations, including a first-generation analog wireless phone service(1G), a second-generation (2G) digital wireless phone service (includinginterim 2.5G and 2.75G networks), a third-generation (3G) high speeddata, Internet-capable wireless service and a fourth-generation (4G)service (e.g., Long Term Evolution (LTE) or WiMax). There are presentlymany different types of wireless communication systems in use, includingcellular and personal communications service (PCS) systems. Examples ofknown cellular systems include the cellular analog advanced mobile phonesystem (AMPS), and digital cellular systems based on code divisionmultiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), the Global System for Mobile access(GSM) variation of TDMA, etc.

A fifth generation (5G) wireless standard, referred to as New Radio(NR), calls for higher data transfer speeds, greater numbers ofconnections, and better coverage, among other improvements. The 5Gstandard, according to the Next Generation Mobile Networks Alliance, isdesigned to provide data rates of several tens of megabits per second toeach of tens of thousands of users, with 1 gigabit per second to tens ofworkers on an office floor. Several hundreds of thousands ofsimultaneous connections should be supported in order to support largesensor deployments. Consequently, the spectral efficiency of 5G mobilecommunications should be significantly enhanced compared to the current4G standard. Furthermore, signaling efficiencies should be enhanced andlatency should be substantially reduced compared to current standards.

To support position estimations in terrestrial wireless networks, amobile device can be configured to measure and report the observed timedifference of arrival (OTDOA) or reference signal timing difference(RSTD) between reference signals received from two or more network nodes(e.g., different base stations or different transmission points (e.g.,antennas) belonging to the same base station).

SUMMARY

The following presents a simplified summary relating to one or moreaspects disclosed herein. Thus, the following summary should not beconsidered an extensive overview relating to all contemplated aspects,nor should the following summary be considered to identify key orcritical elements relating to all contemplated aspects or to delineatethe scope associated with any particular aspect. Accordingly, thefollowing summary has the sole purpose to present certain conceptsrelating to one or more aspects relating to the mechanisms disclosedherein in a simplified form to precede the detailed descriptionpresented below.

In an aspect, a method of wireless communication performed by a userequipment (UE) includes receiving a positioning configuration, thepositioning configuration including at least an identifier of a firstdownlink reference signal from a neighboring cell to be used forestimating a downlink path loss or determining an uplink spatialtransmit beam, determining that the first downlink reference signalreceived from the neighboring cell cannot be used for estimating thedownlink path loss or determining the uplink spatial transmit beam, inresponse to the determination, estimating the downlink path loss ordetermining the uplink spatial transmit beam based on a second downlinkreference signal received from the neighboring cell or a serving cell,and transmitting an uplink reference signal for positioning based on theestimated downlink path loss, the determined uplink spatial transmitbeam, or a combination thereof.

In an aspect, a method of wireless communication performed by a locationserver includes configuring a UE to receive at least a first downlinkreference signal from a neighboring cell to be used to estimate adownlink path loss or determine an uplink spatial transmit beam,receiving, from the UE, a report indicating a signal quality of thefirst downlink reference signal, and based on the signal quality of thefirst downlink reference signal being below a threshold, configuring theUE to receive at least a second downlink reference signal from theneighboring cell or a serving cell to be used to estimate the downlinkpath loss or determine the uplink spatial transmit beam.

In an aspect, a method of wireless communication performed by a UEincludes receiving, from a network node, a configuration to use at leasta first downlink reference signal from a neighboring cell to estimate adownlink path loss or determine an uplink spatial transmit beam,sending, to the network node, a report indicating a signal quality ofthe first downlink reference signal, and based on the signal quality ofthe first downlink reference signal being below a threshold, receiving,from the network node, a configuration to use at least a second downlinkreference signal from the neighboring cell or a serving cell to estimatethe downlink path loss or determine the uplink spatial transmit beam.

In an aspect, a UE includes a memory, at least one transceiver, and atleast one processor communicatively coupled to the memory and the atleast one transceiver, the at least one processor configured to:receive, via the at least one transceiver, a positioning configuration,the positioning configuration including at least an identifier of afirst downlink reference signal from a neighboring cell to be used forestimating a downlink path loss or determining an uplink spatialtransmit beam, determine that the first downlink reference signalreceived from the neighboring cell cannot be used to estimate thedownlink path loss or determine the uplink spatial transmit beam, inresponse to the determination, estimate the downlink path loss ordetermining the uplink spatial transmit beam based on a second downlinkreference signal received from the neighboring cell or a serving cell,and cause the at least one transceiver to transmit an uplink referencesignal for positioning based on the estimated downlink path loss, thedetermined uplink spatial transmit beam, or a combination thereof.

In an aspect, a location server includes a memory, at least one networkinterface, and at least one processor communicatively coupled to thememory and the at least one network interface, the at least oneprocessor configured to: configure a UE to receive at least a firstdownlink reference signal from a neighboring cell to be used to estimatea downlink path loss or determine an uplink spatial transmit beam,receive, from the UE, a report indicating a signal quality of the firstdownlink reference signal, and configure the UE, based on the signalquality of the first downlink reference signal being below a threshold,to receive at least a second downlink reference signal from theneighboring cell or a serving cell to be used to estimate the downlinkpath loss or determine the uplink spatial transmit beam.

In an aspect, a UE includes a memory, at least one transceiver, and atleast one processor communicatively coupled to the memory and the atleast one transceiver, the at least one processor configured to:receive, from a network node, a configuration to use at least a firstdownlink reference signal from a neighboring cell to estimate a downlinkpath loss or determine an uplink spatial transmit beam, send, to thenetwork node, a report indicating a signal quality of the first downlinkreference signal, and receive, from the network node, based on thesignal quality of the first downlink reference signal being below athreshold, a configuration to use at least a second downlink referencesignal from the neighboring cell or a serving cell to estimate thedownlink path loss or determine the uplink spatial transmit beam.

In an aspect, a UE includes means for receiving a positioningconfiguration, the positioning configuration including at least anidentifier of a first downlink reference signal from a neighboring cellto be used for estimating a downlink path loss or determining an uplinkspatial transmit beam, means for determining that the first downlinkreference signal received from the neighboring cell cannot be used toestimate the downlink path loss or determine the uplink spatial transmitbeam, in response to the determination, means for estimating thedownlink path loss or determining the uplink spatial transmit beam basedon a second downlink reference signal received from the neighboring cellor a serving cell, and means for transmitting an uplink reference signalfor positioning based on the estimated downlink path loss, thedetermined uplink spatial transmit beam, or a combination thereof.

In an aspect, a location server includes means for configuring a UE toreceive at least a first downlink reference signal from a neighboringcell to be used to estimate a downlink path loss or determine an uplinkspatial transmit beam, means for receiving, from the UE, a reportindicating a signal quality of the first downlink reference signal, andbased on the signal quality of the first downlink reference signal beingbelow a threshold, means for configuring the UE to receive at least asecond downlink reference signal from the neighboring cell or a servingcell to be used to estimate the downlink path loss or determine theuplink spatial transmit beam.

In an aspect, a UE includes means for receiving, from a network node, aconfiguration to use at least a first downlink reference signal from aneighboring cell to estimate a downlink path loss or determine an uplinkspatial transmit beam, means for sending, to the network node, a reportindicating a signal quality of the first downlink reference signal, andmeans for receiving, from the network node, based on the signal qualityof the first downlink reference signal being below a threshold, aconfiguration to use at least a second downlink reference signal fromthe neighboring cell or a serving cell to estimate the downlink pathloss or determine the uplink spatial transmit beam.

In an aspect, a non-transitory computer-readable medium storingcomputer-executable instructions includes computer-executableinstructions comprising at least one instruction instructing a UE toreceive a positioning configuration, the positioning configurationincluding at least an identifier of a first downlink reference signalfrom a neighboring cell to be used for estimating a downlink path lossor determining an uplink spatial transmit beam, at least one instructioninstructing the UE to determine that the first downlink reference signalreceived from the neighboring cell cannot be used to estimate thedownlink path loss or determine the uplink spatial transmit beam, atleast one instruction instructing the UE to estimate, in response to thedetermination, the downlink path loss or determining the uplink spatialtransmit beam based on a second downlink reference signal received fromthe neighboring cell or a serving cell, and at least one instructioninstructing the UE to transmit an uplink reference signal forpositioning based on the estimated downlink path loss, the determineduplink spatial transmit beam, or a combination thereof.

In an aspect, a non-transitory computer-readable medium storingcomputer-executable instructions includes computer-executableinstructions comprising at least one instruction instructing a locationserver to configure a UE to receive at least a first downlink referencesignal from a neighboring cell to be used to estimate a downlink pathloss or determine an uplink spatial transmit beam, at least oneinstruction instructing the location server to receive, from the UE, areport indicating a signal quality of the first downlink referencesignal, and at least one instruction instructing the location server toconfigure, based on the signal quality of the first downlink referencesignal being below a threshold, the UE to receive at least a seconddownlink reference signal from the neighboring cell or a serving cell tobe used to estimate the downlink path loss or determine the uplinkspatial transmit beam.

In an aspect, a non-transitory computer-readable medium storingcomputer-executable instructions includes computer-executableinstructions comprising at least one instruction instructing a UE toreceive, from a network node, a configuration to use at least a firstdownlink reference signal from a neighboring cell to estimate a downlinkpath loss or determine an uplink spatial transmit beam, at least oneinstruction instructing the UE to send, to the network node, a reportindicating a signal quality of the first downlink reference signal, andat least one instruction instructing the UE to receive, from the networknode, based on the signal quality of the first downlink reference signalbeing below a threshold, a configuration to use at least a seconddownlink reference signal from the neighboring cell or a serving cell toestimate the downlink path loss or determine the uplink spatial transmitbeam.

Other objects and advantages associated with the aspects disclosedherein will be apparent to those skilled in the art based on theaccompanying drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofvarious aspects of the disclosure and are provided solely forillustration of the aspects and not limitation thereof.

FIG. 1 illustrates an exemplary wireless communications system,according to various aspects of the disclosure.

FIGS. 2A and 2B illustrate exemplary wireless network structures,according to various aspects of the disclosure.

FIGS. 3A to 3C are simplified block diagrams of several exemplaryaspects of components that may be employed in wireless communicationnodes and configured to support communication, according to variousaspects of the disclosure.

FIGS. 4A to 4D are diagrams illustrating exemplary frame structures andchannels within the frame structures, according to aspects of thedisclosure.

FIGS. 5A and 5B illustrate exemplary random access procedures, accordingto aspects of the disclosure.

FIG. 6 is a diagram of an exemplary random access-based SpCell beamfailure recovery procedure, according to aspects of the disclosure.

FIG. 7 is a diagram illustrating an exemplary technique for determininga position of a mobile device using information obtained from aplurality of base stations.

FIGS. 8-10 illustrate exemplary methods of wireless communication,according to aspects of the disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure are provided in the following description andrelated drawings directed to various examples provided for illustrationpurposes. Alternate aspects may be devised without departing from thescope of the disclosure. Additionally, well-known elements of thedisclosure will not be described in detail or will be omitted so as notto obscure the relevant details of the disclosure.

The words “exemplary” and/or “example” are used herein to mean “servingas an example, instance, or illustration.” Any aspect described hereinas “exemplary” and/or “example” is not necessarily to be construed aspreferred or advantageous over other aspects. Likewise, the term“aspects of the disclosure” does not require that all aspects of thedisclosure include the discussed feature, advantage or mode ofoperation.

Those of skill in the art will appreciate that the information andsignals described below may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the description below may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof, depending inpart on the particular application, in part on the desired design, inpart on the corresponding technology, etc.

Further, many aspects are described in terms of sequences of actions tobe performed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, the sequence(s)of actions described herein can be considered to be embodied entirelywithin any form of non-transitory computer-readable storage mediumhaving stored therein a corresponding set of computer instructions that,upon execution, would cause or instruct an associated processor of adevice to perform the functionality described herein. Thus, the variousaspects of the disclosure may be embodied in a number of differentforms, all of which have been contemplated to be within the scope of theclaimed subject matter. In addition, for each of the aspects describedherein, the corresponding form of any such aspects may be describedherein as, for example, “logic configured to” perform the describedaction.

As used herein, the terms “user equipment” (UE) and “base station” arenot intended to be specific or otherwise limited to any particular radioaccess technology (RAT), unless otherwise noted. In general, a UE may beany wireless communication device (e.g., a mobile phone, router, tabletcomputer, laptop computer, tracking device, wearable (e.g., smartwatch,glasses, augmented reality (AR)/virtual reality (VR) headset, etc.),vehicle (e.g., automobile, motorcycle, bicycle, etc.), Internet ofThings (IoT) device, etc.) used by a user to communicate over a wirelesscommunications network. A UE may be mobile or may (e.g., at certaintimes) be stationary, and may communicate with a radio access network(RAN). As used herein, the term “UE” may be referred to interchangeablyas an “access terminal” or “AT,” a “client device,” a “wireless device,”a “subscriber device,” a “subscriber terminal,” a “subscriber station,”a “user terminal” or UT, a “mobile terminal,” a “mobile station,” orvariations thereof. Generally, UEs can communicate with a core networkvia a RAN, and through the core network the UEs can be connected withexternal networks such as the Internet and with other UEs. Of course,other mechanisms of connecting to the core network and/or the Internetare also possible for the UEs, such as over wired access networks,wireless local area network (WLAN) networks (e.g., based on IEEE 802.11,etc.) and so on.

A base station may operate according to one of several RATs incommunication with UEs depending on the network in which it is deployed,and may be alternatively referred to as an access point (AP), a networknode, a NodeB, an evolved NodeB (eNB), a New Radio (NR) Node B (alsoreferred to as a gNB or gNodeB), etc. In addition, in some systems abase station may provide purely edge node signaling functions while inother systems it may provide additional control and/or networkmanagement functions. A communication link through which UEs can sendsignals to a base station is called an uplink (UL) channel (e.g., areverse traffic channel, a reverse control channel, an access channel,etc.). A communication link through which the base station can sendsignals to UEs is called a downlink (DL) or forward link channel (e.g.,a paging channel, a control channel, a broadcast channel, a forwardtraffic channel, etc.). As used herein the term traffic channel (TCH)can refer to either an uplink/reverse or downlink/forward trafficchannel.

The term “base station” may refer to a single physicaltransmission-reception point (TRP) or to multiple physical TRPs that mayor may not be co-located. For example, where the term “base station”refers to a single physical TRP, the physical TRP may be an antenna ofthe base station corresponding to a cell of the base station. Where theterm “base station” refers to multiple co-located physical TRPs, thephysical TRPs may be an array of antennas (e.g., as in a multiple-inputmultiple-output (MIMO) system or where the base station employsbeamforming) of the base station. Where the term “base station” refersto multiple non-co-located physical TRPs, the physical TRPs may be adistributed antenna system (DAS) (a network of spatially separatedantennas connected to a common source via a transport medium) or aremote radio head (RRH) (a remote base station connected to a servingbase station). Alternatively, the non-co-located physical TRPs may bethe serving base station receiving the measurement report from the UEand a neighbor base station whose reference signals the UE is measuring.Because a TRP is the point from which a base station transmits andreceives wireless signals, as used herein, references to transmissionfrom or reception at a base station are to be understood as referring toa particular TRP of the base station.

A radio frequency (RF) signal comprises an electromagnetic wave of agiven frequency that transports information through the space between atransmitter and a receiver. As used herein, a transmitter may transmit asingle RF signal or multiple RF signals to a receiver. However, thereceiver may receive multiple RF signals corresponding to eachtransmitted RF signal due to the propagation characteristics of RFsignals through multipath channels. The same transmitted RF signal ondifferent paths between the transmitter and receiver may be referred toas a “multipath” RF signal.

According to various aspects, FIG. 1 illustrates an exemplary wirelesscommunications system 100. The wireless communications system 100 (whichmay also be referred to as a wireless wide area network (WWAN)) mayinclude various base stations 102 (labeled “BS”) and various UEs 104.The base stations 102 may include macro cell base stations (high powercellular base stations) and/or small cell base stations (low powercellular base stations). In an aspect, the macro cell base stations 102may include eNBs where the wireless communications system 100corresponds to an LTE network, or gNBs where the wireless communicationssystem 100 corresponds to an NR network, or a combination of both, andthe small cell base stations 102′ may include femtocells, picocells,microcells, etc.

The base stations 102 may collectively form a RAN and interface with acore network 170 (e.g., an evolved packet core (EPC) or next generationcore (NGC)) through backhaul links 122, and through the core network 170to one or more location servers 172. In addition to other functions, thebase stations 102 may perform functions that relate to one or more oftransferring user data, radio channel ciphering and deciphering,integrity protection, header compression, mobility control functions(e.g., handover, dual connectivity), inter-cell interferencecoordination, connection setup and release, load balancing, distributionfor non-access stratum (NAS) messages, NAS node selection,synchronization, RAN sharing, multimedia broadcast multicast service(MBMS), subscriber and equipment trace, RAN information management(RIM), paging, positioning, and delivery of warning messages. The basestations 102 may communicate with each other directly or indirectly(e.g., through the EPC/NGC) over backhaul links 134, which may be wiredor wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. In an aspect, one or more cellsmay be supported by a base station 102 in each geographic coverage area110. A “cell” is a logical communication entity used for communicationwith a base station (e.g., over some frequency resource, referred to asa carrier frequency, component carrier, carrier, band, or the like), andmay be associated with an identifier (e.g., a physical cell identifier(PCI), a virtual cell identifier (VCI)) for distinguishing cellsoperating via the same or a different carrier frequency. In some cases,different cells may be configured according to different protocol types(e.g., machine-type communication (MTC), narrowband IoT (NB-IoT),enhanced mobile broadband (eMBB), or others) that may provide access fordifferent types of UEs. Because a cell is supported by a specific basestation, the term “cell” may refer to either or both the logicalcommunication entity and the base station that supports it, depending onthe context. In some cases, the term “cell” may also refer to ageographic coverage area of a base station (e.g., a sector), insofar asa carrier frequency can be detected and used for communication withinsome portion of geographic coverage areas 110.

While neighboring macro cell base station 102 geographic coverage areas110 may partially overlap (e.g., in a handover region), some of thegeographic coverage areas 110 may be substantially overlapped by alarger geographic coverage area 110. For example, a small cell basestation 102′ (labeled “SC” for “small cell”) may have a geographiccoverage area 110′ that substantially overlaps with the geographiccoverage area 110 of one or more macro cell base stations 102. A networkthat includes both small cell and macro cell base stations may be knownas a heterogeneous network. A heterogeneous network may also includehome eNBs (HeNBs), which may provide service to a restricted group knownas a closed subscriber group (CSG).

The communication links 120 between the base stations 102 and the UEs104 may include uplink (also referred to as reverse link) transmissionsfrom a UE 104 to a base station 102 and/or downlink (DL) (also referredto as forward link) transmissions from a base station 102 to a UE 104.The communication links 120 may use MIMO antenna technology, includingspatial multiplexing, beamforming, and/or transmit diversity. Thecommunication links 120 may be through one or more carrier frequencies.Allocation of carriers may be asymmetric with respect to downlink anduplink (e.g., more or less carriers may be allocated for downlink thanfor UL).

The wireless communications system 100 may further include a wirelesslocal area network (WLAN) access point (AP) 150 in communication withone or more WLAN stations (STAs) 152 via communication links 154 in anunlicensed frequency spectrum (e.g., 5 GHz). When communicating in anunlicensed frequency spectrum, the WLAN STAs 152 and/or the WLAN AP 150may perform a clear channel assessment (CCA) or listen before talk (LBT)procedure prior to communicating in order to determine whether thechannel is available.

The small cell base station 102′ may operate in a licensed and/or anunlicensed frequency spectrum. When operating in an unlicensed frequencyspectrum, the small cell base station 102′ may employ LTE or NRtechnology and use the same 5 GHz unlicensed frequency spectrum as usedby the WLAN AP 150. The small cell base station 102′, employing LTE/5Gin an unlicensed frequency spectrum, may boost coverage to and/orincrease capacity of the access network. NR in unlicensed spectrum maybe referred to as NR-U. LTE in an unlicensed spectrum may be referred toas LTE-U, licensed assisted access (LAA), or MulteFire.

The wireless communications system 100 may further include a millimeterwave (mmW) base station 180 that may operate in mmW frequencies and/ornear mmW frequencies in communication with a UE 182. Extremely highfrequency (EHF) is part of the RF in the electromagnetic spectrum. EHFhas a range of 30 GHz to 300 GHz and a wavelength between 1 millimeterand 10 millimeters. Radio waves in this band may be referred to as amillimeter wave. Near mmW may extend down to a frequency of 3 GHz with awavelength of 100 millimeters. The super high frequency (SHF) bandextends between 3 GHz and 30 GHz, also referred to as centimeter wave.Communications using the mmW/near mmW radio frequency band have a highpath loss and a relatively short range. The mmW base station 180 and theUE 182 may utilize beamforming (transmit and/or receive) over an mmWcommunication link 184 to compensate for the extremely high path lossand short range. Further, it will be appreciated that in alternativeconfigurations, one or more base stations 102 may also transmit usingmmW or near mmW and beamforming. Accordingly, it will be appreciatedthat the foregoing illustrations are merely examples and should not beconstrued to limit the various aspects disclosed herein.

Transmit beamforming is a technique for focusing an RF signal in aspecific direction. Traditionally, when a network node (e.g., a basestation) broadcasts an RF signal, it broadcasts the signal in alldirections (omni-directionally). With transmit beamforming, the networknode determines where a given target device (e.g., a UE) is located(relative to the transmitting network node) and projects a strongerdownlink RF signal in that specific direction, thereby providing afaster (in terms of data rate) and stronger RF signal for the receivingdevice(s). To change the directionality of the RF signal whentransmitting, a network node can control the phase and relativeamplitude of the RF signal at each of the one or more transmitters thatare broadcasting the RF signal. For example, a network node may use anarray of antennas (referred to as a “phased array” or an “antennaarray”) that creates a beam of RF waves that can be “steered” to pointin different directions, without actually moving the antennas.Specifically, the RF current from the transmitter is fed to theindividual antennas with the correct phase relationship so that theradio waves from the separate antennas add together to increase theradiation in a desired direction, while cancelling to suppress radiationin undesired directions.

Transmit beams may be quasi-collocated, meaning that they appear to thereceiver (e.g., a UE) as having the same parameters, regardless ofwhether or not the transmitting antennas of the network node themselvesare physically collocated. In NR, there are four types ofquasi-collocation (QCL) relations. Specifically, a QCL relation of agiven type means that certain parameters about a second reference signalon a second beam can be derived from information about a sourcereference signal on a source beam. Thus, if the source reference signalis QCL Type A, the receiver can use the source reference signal toestimate the Doppler shift, Doppler spread, average delay, and delayspread of a second reference signal transmitted on the same channel. Ifthe source reference signal is QCL Type B, the receiver can use thesource reference signal to estimate the Doppler shift and Doppler spreadof a second reference signal transmitted on the same channel. If thesource reference signal is QCL Type C, the receiver can use the sourcereference signal to estimate the Doppler shift and average delay of asecond reference signal transmitted on the same channel. If the sourcereference signal is QCL Type D, the receiver can use the sourcereference signal to estimate the spatial receive parameter of a secondreference signal transmitted on the same channel.

In receive beamforming, the receiver uses a receive beam to amplify RFsignals detected on a given channel. For example, the receiver canincrease the gain setting and/or adjust the phase setting of an array ofantennas in a particular direction to amplify (e.g., to increase thegain level of) the RF signals received from that direction. Thus, when areceiver is said to beamform in a certain direction, it means the beamgain in that direction is high relative to the beam gain along otherdirections, or the beam gain in that direction is the highest comparedto the beam gain in that direction of all other receive beams availableto the receiver. This results in a stronger received signal strength(e.g., reference signal received power (RSRP), reference signal receivedquality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) ofthe RF signals received from that direction.

Transmit and receive beams may be spatially related. A spatial relationmeans that parameters for a second beam (e.g., a transmit or receivebeam) for a second reference signal can be derived from informationabout a first beam (e.g., a receive beam or a transmit beam) for a firstreference signal. For example, a UE may use a particular receive beam toreceive a reference downlink reference signal (e.g., synchronizationsignal block (SSB)) from a base station. The UE can then form a transmitbeam for sending an uplink reference signal (e.g., sounding referencesignal (SRS)) to that base station based on the parameters of thereceive beam.

Note that a “downlink” beam may be either a transmit beam or a receivebeam, depending on the entity forming it. For example, if a base stationis forming the downlink beam to transmit a reference signal to a UE, thedownlink beam is a transmit beam. If the UE is forming the downlinkbeam, however, it is a receive beam to receive the downlink referencesignal. Similarly, an “uplink” beam may be either a transmit beam or areceive beam, depending on the entity forming it. For example, if a basestation is forming the uplink beam, it is an uplink receive beam, and ifa UE is forming the uplink beam, it is an uplink transmit beam.

In 5G, the frequency spectrum in which wireless nodes (e.g., basestations 102/180, UEs 104/182) operate is divided into multiplefrequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600MHz), FR3 (above 52600 MHz), and FR4 (between FR1 and FR2). In amulti-carrier system, such as 5G, one of the carrier frequencies isreferred to as the “primary carrier” or “anchor carrier” or “primaryserving cell” or “PCell,” and the remaining carrier frequencies arereferred to as “secondary carriers” or “secondary serving cells” or“SCells.” In carrier aggregation, the anchor carrier is the carrieroperating on the primary frequency (e.g., FR1) utilized by a UE 104/182and the cell in which the UE 104/182 either performs the initial radioresource control (RRC) connection establishment procedure or initiatesthe RRC connection re-establishment procedure. The primary carriercarries all common and UE-specific control channels, and may be acarrier in a licensed frequency (however, this is not always the case).A secondary carrier is a carrier operating on a second frequency (e.g.,FR2) that may be configured once the RRC connection is establishedbetween the UE 104 and the anchor carrier and that may be used toprovide additional radio resources. In some cases, the secondary carriermay be a carrier in an unlicensed frequency. The secondary carrier maycontain only necessary signaling information and signals, for example,those that are UE-specific may not be present in the secondary carrier,since both primary uplink and downlink carriers are typicallyUE-specific. This means that different UEs 104/182 in a cell may havedifferent downlink primary carriers. The same is true for the uplinkprimary carriers. The network is able to change the primary carrier ofany UE 104/182 at any time. This is done, for example, to balance theload on different carriers. Because a “serving cell” (whether a PCell oran SCell) corresponds to a carrier frequency/component carrier overwhich some base station is communicating, the term “cell,” “servingcell,” “component carrier,” “carrier frequency,” and the like can beused interchangeably.

For example, still referring to FIG. 1, one of the frequencies utilizedby the macro cell base stations 102 may be an anchor carrier (or“PCell”) and other frequencies utilized by the macro cell base stations102 and/or the mmW base station 180 may be secondary carriers(“SCells”). The simultaneous transmission and/or reception of multiplecarriers enables the UE 104/182 to significantly increase its datatransmission and/or reception rates. For example, two 20 MHz aggregatedcarriers in a multi-carrier system would theoretically lead to atwo-fold increase in data rate (i.e., 40 MHz), compared to that attainedby a single 20 MHz carrier.

The wireless communications system 100 may further include one or moreUEs, such as UE 190, that connects indirectly to one or morecommunication networks via one or more device-to-device (D2D)peer-to-peer (P2P) links. In the example of FIG. 1, UE 190 has a D2D P2Plink 192 with one of the UEs 104 connected to one of the base stations102 (e.g., through which UE 190 may indirectly obtain cellularconnectivity) and a D2D P2P link 194 with WLAN STA 152 connected to theWLAN AP 150 (through which UE 190 may indirectly obtain WLAN-basedInternet connectivity). In an example, the D2D P2P links 192 and 194 maybe supported with any well-known D2D RAT, such as LTE Direct (LTE-D),WiFi Direct (WiFi-D), Bluetooth®, and so on.

The wireless communications system 100 may further include a UE 164 thatmay communicate with a macro cell base station 102 over a communicationlink 120 and/or the mmW base station 180 over a mmW communication link184. For example, the macro cell base station 102 may support a PCelland one or more SCells for the UE 164 and the mmW base station 180 maysupport one or more SCells for the UE 164.

According to various aspects, FIG. 2A illustrates an exemplary wirelessnetwork structure 200. For example, an NGC 210 (also referred to as a“5GC”) can be viewed functionally as control plane functions (C-plane)214 (e.g., UE registration, authentication, network access, gatewayselection, etc.) and user plane functions (U-plane) 212 (e.g., UEgateway function, access to data networks, IP routing, etc.), whichoperate cooperatively to form the core network. User plane interface(NG-U) 213 and control plane interface (NG-C) 215 connect the gNB 222 tothe NGC 210 and specifically to the user plane functions 212 and controlplane functions 214, respectively. In an additional configuration, aneNB 224 may also be connected to the NGC 210 via NG-C 215 to the controlplane functions 214 and NG-U 213 to user plane functions 212. Further,eNB 224 may directly communicate with gNB 222 via a backhaul connection223. In some configurations, the New RAN 220 may only have one or moregNBs 222, while other configurations include one or more of both eNBs224 and gNBs 222. Either gNB 222 or eNB 224 may communicate with UEs 204(e.g., any of the UEs depicted in FIG. 1). Another optional aspect mayinclude location server 230, which may be in communication with the NGC210 to provide location assistance for UEs 204. The location server 230can be implemented as a plurality of separate servers (e.g., physicallyseparate servers, different software modules on a single server,different software modules spread across multiple physical servers,etc.), or alternately may each correspond to a single server. Thelocation server 230 can be configured to support one or more locationservices for UEs 204 that can connect to the location server 230 via thecore network, NGC 210, and/or via the Internet (not illustrated).Further, the location server 230 may be integrated into a component ofthe core network, or alternatively may be external to the core network.

According to various aspects, FIG. 2B illustrates another exemplarywireless network structure 250. For example, an NGC 260 (also referredto as a “5GC”) can be viewed functionally as control plane functions,provided by an access and mobility management function (AMF)/user planefunction (UPF) 264, and user plane functions, provided by a sessionmanagement function (SMF) 262, which operate cooperatively to form thecore network (i.e., NGC 260). User plane interface 263 and control planeinterface 265 connect the eNB 224 to the NGC 260 and specifically to SMF262 and AMF/UPF 264, respectively. In an additional configuration, a gNB222 may also be connected to the NGC 260 via control plane interface 265to AMF/UPF 264 and user plane interface 263 to SMF 262. Further, eNB 224may directly communicate with gNB 222 via the backhaul connection 223,with or without gNB direct connectivity to the NGC 260. In someconfigurations, the New RAN 220 may only have one or more gNBs 222,while other configurations include one or more of both eNBs 224 and gNBs222. Either gNB 222 or eNB 224 may communicate with UEs 204 (e.g., anyof the UEs depicted in FIG. 1). The base stations of the New RAN 220communicate with the AMF-side of the AMF/UPF 264 over the N2 interfaceand the UPF-side of the AMF/UPF 264 over the N3 interface.

The functions of the AMF include registration management, connectionmanagement, reachability management, mobility management, lawfulinterception, transport for session management (SM) messages between theUE 204 and the SMF 262, transparent proxy services for routing SMmessages, access authentication and access authorization, transport forshort message service (SMS) messages between the UE 204 and the shortmessage service function (SMSF) (not shown), and security anchorfunctionality (SEAF). The AMF also interacts with the authenticationserver function (AUSF) (not shown) and the UE 204, and receives theintermediate key that was established as a result of the UE 204authentication process. In the case of authentication based on a UMTS(universal mobile telecommunications system) subscriber identity module(USIM), the AMF retrieves the security material from the AUSF. Thefunctions of the AMF also include security context management (SCM). TheSCM receives a key from the SEAF that it uses to derive access-networkspecific keys. The functionality of the AMF also includes locationservices management for regulatory services, transport for locationservices messages between the UE 204 and the location managementfunction (LMF) 270, as well as between the New RAN 220 and the LMF 270,evolved packet system (EPS) bearer identifier allocation forinterworking with the EPS, and UE 204 mobility event notification. Inaddition, the AMF also supports functionalities for non-3GPP accessnetworks.

Functions of the UPF include acting as an anchor point forintra-/inter-RAT mobility (when applicable), acting as an externalprotocol data unit (PDU) session point of interconnect to the datanetwork (not shown), providing packet routing and forwarding, packetinspection, user plane policy rule enforcement (e.g., gating,redirection, traffic steering), lawful interception (user planecollection), traffic usage reporting, quality of service (QoS) handlingfor the user plane (e.g., UL/DL rate enforcement, reflective QoS markingin the DL), uplink traffic verification (service data flow (SDF) to QoSflow mapping), transport level packet marking in the uplink and DL,downlink packet buffering and downlink data notification triggering, andsending and forwarding of one or more “end markers” to the source RANnode.

The functions of the SMF 262 include session management, UE Internetprotocol (IP) address allocation and management, selection and controlof user plane functions, configuration of traffic steering at the UPF toroute traffic to the proper destination, control of part of policyenforcement and QoS, and downlink data notification. The interface overwhich the SMF 262 communicates with the AMF-side of the AMF/UPF 264 isreferred to as the N11 interface.

Another optional aspect may include a LMF 270, which may be incommunication with the NGC 260 to provide location assistance for UEs204. The LMF 270 can be implemented as a plurality of separate servers(e.g., physically separate servers, different software modules on asingle server, different software modules spread across multiplephysical servers, etc.), or alternately may each correspond to a singleserver. The LMF 270 can be configured to support one or more locationservices for UEs 204 that can connect to the LMF 270 via the corenetwork, NGC 260, and/or via the Internet (not illustrated).

FIGS. 3A, 3B, and 3C illustrate several exemplary components(represented by corresponding blocks) that may be incorporated into a UE302 (which may correspond to any of the UEs described herein), a basestation 304 (which may correspond to any of the base stations describedherein), and a network entity 306 (which may correspond to or embody anyof the network functions described herein, including the location server230 and the LMF 270) to support the file transmission operations astaught herein. It will be appreciated that these components may beimplemented in different types of apparatuses in differentimplementations (e.g., in an ASIC, in a system-on-chip (SoC), etc.). Theillustrated components may also be incorporated into other apparatusesin a communication system. For example, other apparatuses in a systemmay include components similar to those described to provide similarfunctionality. Also, a given apparatus may contain one or more of thecomponents. For example, an apparatus may include multiple transceivercomponents that enable the apparatus to operate on multiple carriersand/or communicate via different technologies.

The UE 302 and the base station 304 each include wireless wide areanetwork (WWAN) transceiver 310 and 350, respectively, configured tocommunicate via one or more wireless communication networks (not shown),such as an NR network, an LTE network, a GSM network, and/or the like.The WWAN transceivers 310 and 350 may be connected to one or moreantennas 316 and 356, respectively, for communicating with other networknodes, such as other UEs, access points, base stations (e.g., eNBs,gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.)over a wireless communication medium of interest (e.g., some set oftime/frequency resources in a particular frequency spectrum). The WWANtransceivers 310 and 350 may be variously configured for transmittingand encoding signals 318 and 358 (e.g., messages, indications,information, and so on), respectively, and, conversely, for receivingand decoding signals 318 and 358 (e.g., messages, indications,information, pilots, and so on), respectively, in accordance with thedesignated RAT. Specifically, the WWAN transceivers 310 and 350 includeone or more transmitters 314 and 354, respectively, for transmitting andencoding signals 318 and 358, respectively, and one or more receivers312 and 352, respectively, for receiving and decoding signals 318 and358, respectively.

The UE 302 and the base station 304 also include, at least in somecases, wireless local area network (WLAN) transceivers 320 and 360,respectively. The WLAN transceivers 320 and 360 may be connected to oneor more antennas 326 and 366, respectively, for communicating with othernetwork nodes, such as other UEs, access points, base stations, etc.,via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth®, etc.)over a wireless communication medium of interest. The WLAN transceivers320 and 360 may be variously configured for transmitting and encodingsignals 328 and 368 (e.g., messages, indications, information, and soon), respectively, and, conversely, for receiving and decoding signals328 and 368 (e.g., messages, indications, information, pilots, and soon), respectively, in accordance with the designated RAT. Specifically,the WLAN transceivers 320 and 360 include one or more transmitters 324and 364, respectively, for transmitting and encoding signals 328 and368, respectively, and one or more receivers 322 and 362, respectively,for receiving and decoding signals 328 and 368, respectively.

Transceiver circuitry including at least one transmitter and at leastone receiver may comprise an integrated device (e.g., embodied as atransmitter circuit and a receiver circuit of a single communicationdevice) in some implementations, may comprise a separate transmitterdevice and a separate receiver device in some implementations, or may beembodied in other ways in other implementations. In an aspect, atransmitter may include or be coupled to a plurality of antennas (e.g.,antennas 316, 326, 356, 366), such as an antenna array, that permits therespective apparatus to perform transmit “beamforming,” as describedherein. Similarly, a receiver may include or be coupled to a pluralityof antennas (e.g., antennas 316, 326, 356, 366), such as an antennaarray, that permits the respective apparatus to perform receivebeamforming, as described herein. In an aspect, the transmitter andreceiver may share the same plurality of antennas (e.g., antennas 316,326, 356, 366), such that the respective apparatus can only receive ortransmit at a given time, not both at the same time. A wirelesscommunication device (e.g., one or both of the transceivers 310 and 320and/or 350 and 360) of the UE 302 and/or the base station 304 may alsocomprise a network listen module (NLM) or the like for performingvarious measurements.

The UE 302 and the base station 304 also include, at least in somecases, satellite positioning systems (SPS) receivers 330 and 370,respectively. The SPS receivers 330 and 370 may be connected to one ormore antennas 336 and 376, respectively, for receiving SPS signals 338and 378, respectively, such as global positioning system (GPS) signals,global navigation satellite system (GLONASS) signals, Galileo signals,Beidou signals, Indian Regional Navigation Satellite System (NAVIC),Quasi-Zenith Satellite System (QZSS), etc. The SPS receivers 330 and 370may comprise any suitable hardware and/or software for receiving andprocessing SPS signals 338 and 378, respectively. The SPS receivers 330and 370 request information and operations as appropriate from the othersystems, and perform calculations necessary to determine positions ofthe UE 302 and the base station 304, respectively, using measurementsobtained by any suitable SPS algorithm.

The base station 304 and the network entity 306 each include at leastone network interface 380 and 390, respectively, for communicating withother network entities. For example, the network interfaces 380 and 390(e.g., one or more network access ports) may be configured tocommunicate with one or more network entities via a wire-based orwireless backhaul connection. In some aspects, the network interfaces380 and 390 may be implemented as transceivers configured to supportwire-based or wireless signal communication. This communication mayinvolve, for example, sending and receiving messages, parameters, and/orother types of information.

The UE 302, the base station 304, and the network entity 306 alsoinclude other components that may be used in conjunction with theoperations as disclosed herein. The UE 302 includes processor circuitryimplementing a processing system 332 for providing functionalityrelating to, for example, positioning operations, and for providingother processing functionality. The base station 304 includes aprocessing system 384 for providing functionality relating to, forexample, positioning operations as disclosed herein, and for providingother processing functionality. The network entity 306 includes aprocessing system 394 for providing functionality relating to, forexample, positioning operations as disclosed herein, and for providingother processing functionality. In an aspect, the processing systems332, 384, and 394 may include, for example, one or more general purposeprocessors, multi-core processors, ASICs, digital signal processors(DSPs), field programmable gate arrays (FPGA), or other programmablelogic devices or processing circuitry.

The UE 302, the base station 304, and the network entity 306 includememory circuitry implementing memory components 340, 386, and 396 (e.g.,each including a memory device), respectively, for maintaininginformation (e.g., information indicative of reserved resources,thresholds, parameters, and so on). In some cases, the UE 302, the basestation 304, and the network entity 306 may include positioningcomponents 342, 388, and 398, respectively. The positioning components342, 388, and 398 may be hardware circuits that are part of or coupledto the processing systems 332, 384, and 394, respectively, that, whenexecuted, cause the UE 302, the base station 304, and the network entity306 to perform the functionality described herein. In other aspects, thepositioning components 342, 388, and 398 may be external to theprocessing systems 332, 384, and 394 (e.g., part of a modem processingsystem, integrated with another processing system, etc.), respectively.Alternatively, the positioning components 342, 388, and 398 may bememory modules (as shown in FIGS. 3A-C) stored in the memory components340, 386, and 396, respectively, that, when executed by the processingsystems 332, 384, and 394 (or a modem processing system, anotherprocessing system, etc.), cause the UE 302, the base station 304, andthe network entity 306 to perform the functionality described herein.

The UE 302 may include one or more sensors 344 coupled to the processingsystem 332 to provide movement and/or orientation information that isindependent of motion data derived from signals received by the WWANtransceiver 310, the WLAN transceiver 320, and/or the SPS receiver 330.By way of example, the sensor(s) 344 may include an accelerometer (e.g.,a micro-electrical mechanical systems (MEMS) device), a gyroscope, ageomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometricpressure altimeter), and/or any other type of movement detection sensor.Moreover, the sensor(s) 344 may include a plurality of different typesof devices and combine their outputs in order to provide motioninformation. For example, the sensor(s) 344 may use a combination of amulti-axis accelerometer and orientation sensors to provide the abilityto compute positions in 2D and/or 3D coordinate systems.

In addition, the UE 302 includes a user interface 346 for providingindications (e.g., audible and/or visual indications) to a user and/orfor receiving user input (e.g., upon user actuation of a sensing devicesuch a keypad, a touch screen, a microphone, and so on). Although notshown, the base station 304 and the network entity 306 may also includeuser interfaces.

Referring to the processing system 384 in more detail, in the downlink,IP packets from the network entity 306 may be provided to the processingsystem 384. The processing system 384 may implement functionality for anRRC layer, a packet data convergence protocol (PDCP) layer, a radio linkcontrol (RLC) layer, and a medium access control (MAC) layer. Theprocessing system 384 may provide RRC layer functionality associatedwith broadcasting of system information (e.g., master information block(MIB), system information blocks (SIBs)), RRC connection control (e.g.,RRC connection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter-RAT mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough automatic repeat request (ARQ), concatenation, segmentation, andreassembly of RLC service data units (SDUs), re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,scheduling information reporting, error correction, priority handling,and logical channel prioritization.

The transmitter 354 and the receiver 352 may implement Layer-1functionality associated with various signal processing functions.Layer-1, which includes a physical (PHY) layer, may include errordetection on the transport channels, forward error correction (FEC)coding/decoding of the transport channels, interleaving, rate matching,mapping onto physical channels, modulation/demodulation of physicalchannels, and MIMO antenna processing. The transmitter 354 handlesmapping to signal constellations based on various modulation schemes(e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an orthogonalfrequency division multiplexing (OFDM) subcarrier, multiplexed with areference signal (e.g., pilot) in the time and/or frequency domain, andthen combined together using an inverse fast Fourier transform (IFFT) toproduce a physical channel carrying a time domain OFDM symbol stream.The OFDM symbol stream is spatially precoded to produce multiple spatialstreams. Channel estimates from a channel estimator may be used todetermine the coding and modulation scheme, as well as for spatialprocessing. The channel estimate may be derived from a reference signaland/or channel condition feedback transmitted by the UE 302. Eachspatial stream may then be provided to one or more different antennas356. The transmitter 354 may modulate an RF carrier with a respectivespatial stream for transmission.

At the UE 302, the receiver 312 receives a signal through its respectiveantenna(s) 316. The receiver 312 recovers information modulated onto anRF carrier and provides the information to the processing system 332.The transmitter 314 and the receiver 312 implement Layer-1 functionalityassociated with various signal processing functions. The receiver 312may perform spatial processing on the information to recover any spatialstreams destined for the UE 302. If multiple spatial streams aredestined for the UE 302, they may be combined by the receiver 312 into asingle OFDM symbol stream. The receiver 312 then converts the OFDMsymbol stream from the time-domain to the frequency domain using a fastFourier transform (FFT). The frequency domain signal comprises aseparate OFDM symbol stream for each subcarrier of the OFDM signal. Thesymbols on each subcarrier, and the reference signal, are recovered anddemodulated by determining the most likely signal constellation pointstransmitted by the base station 304. These soft decisions may be basedon channel estimates computed by a channel estimator. The soft decisionsare then decoded and de-interleaved to recover the data and controlsignals that were originally transmitted by the base station 304 on thephysical channel. The data and control signals are then provided to theprocessing system 332, which implements Layer-3 and Layer-2functionality.

In the UL, the processing system 332 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, and control signal processing to recover IP packets fromthe core network. The processing system 332 is also responsible forerror detection.

Similar to the functionality described in connection with the downlinktransmission by the base station 304, the processing system 332 providesRRC layer functionality associated with system information (e.g., MIB,SIBs) acquisition, RRC connections, and measurement reporting; PDCPlayer functionality associated with header compression/decompression,and security (ciphering, deciphering, integrity protection, integrityverification); RLC layer functionality associated with the transfer ofupper layer PDUs, error correction through ARQ, concatenation,segmentation, and reassembly of RLC SDUs, re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing ofMAC SDUs from TBs, scheduling information reporting, error correctionthrough hybrid automatic repeat request (HARQ), priority handling, andlogical channel prioritization.

Channel estimates derived by the channel estimator from a referencesignal or feedback transmitted by the base station 304 may be used bythe transmitter 314 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the transmitter 314 may be provided to different antenna(s)316. The transmitter 314 may modulate an RF carrier with a respectivespatial stream for transmission.

The uplink transmission is processed at the base station 304 in a mannersimilar to that described in connection with the receiver function atthe UE 302. The receiver 352 receives a signal through its respectiveantenna(s) 356. The receiver 352 recovers information modulated onto anRF carrier and provides the information to the processing system 384.

In the UL, the processing system 384 provides demultiplexing betweentransport and logical channels, packet reassembly, deciphering, headerdecompression, control signal processing to recover IP packets from theUE 302. IP packets from the processing system 384 may be provided to thecore network. The processing system 384 is also responsible for errordetection.

For convenience, the UE 302, the base station 304, and/or the networkentity 306 are shown in FIGS. 3A-C as including various components thatmay be configured according to the various examples described herein. Itwill be appreciated, however, that the illustrated blocks may havedifferent functionality in different designs.

The various components of the UE 302, the base station 304, and thenetwork entity 306 may communicate with each other over data buses 334,382, and 392, respectively. The components of FIGS. 3A-C may beimplemented in various ways. In some implementations, the components ofFIGS. 3A-C may be implemented in one or more circuits such as, forexample, one or more processors and/or one or more ASICs (which mayinclude one or more processors). Here, each circuit may use and/orincorporate at least one memory component for storing information orexecutable code used by the circuit to provide this functionality. Forexample, some or all of the functionality represented by blocks 310 to346 may be implemented by processor and memory component(s) of the UE302 (e.g., by execution of appropriate code and/or by appropriateconfiguration of processor components). Similarly, some or all of thefunctionality represented by blocks 350 to 388 may be implemented byprocessor and memory component(s) of the base station 304 (e.g., byexecution of appropriate code and/or by appropriate configuration ofprocessor components). Also, some or all of the functionalityrepresented by blocks 390 to 398 may be implemented by processor andmemory component(s) of the network entity 306 (e.g., by execution ofappropriate code and/or by appropriate configuration of processorcomponents). For simplicity, various operations, acts, and/or functionsare described herein as being performed “by a UE,” “by a base station,”“by a positioning entity,” etc. However, as will be appreciated, suchoperations, acts, and/or functions may actually be performed by specificcomponents or combinations of components of the UE, base station,positioning entity, etc., such as the processing systems 332, 384, 394,the transceivers 310, 320, 350, and 360, the memory components 340, 386,and 396, the positioning components 342, 388, and 398, etc.

Various frame structures may be used to support downlink and uplinktransmissions between network nodes (e.g., base stations and UEs). FIG.4A is a diagram 400 illustrating an example of a downlink framestructure, according to aspects of the disclosure. FIG. 4B is a diagram430 illustrating an example of channels within the downlink framestructure, according to aspects of the disclosure. FIG. 4C is a diagram450 illustrating an example of an uplink frame structure, according toaspects of the disclosure. FIG. 4D is a diagram 480 illustrating anexample of channels within an uplink frame structure, according toaspects of the disclosure. Other wireless communications technologiesmay have different frame structures and/or different channels.

LTE, and in some cases NR, utilizes OFDM on the downlink andsingle-carrier frequency division multiplexing (SC-FDM) on the uplink.Unlike LTE, however, NR has an option to use OFDM on the uplink as well.OFDM and SC-FDM partition the system bandwidth into multiple (K)orthogonal subcarriers, which are also commonly referred to as tones,bins, etc. Each subcarrier may be modulated with data. In general,modulation symbols are sent in the frequency domain with OFDM and in thetime domain with SC-FDM. The spacing between adjacent subcarriers may befixed, and the total number of subcarriers (K) may be dependent on thesystem bandwidth. For example, the spacing of the subcarriers may be 15kHz and the minimum resource allocation (resource block) may be 12subcarriers (or 180 kHz). Consequently, the nominal FFT size may beequal to 128, 256, 512, 1024, or 2048 for system bandwidth of 1.25, 2.5,5, 10, or 20 megahertz (MHz), respectively. The system bandwidth mayalso be partitioned into subbands. For example, a subband may cover 1.08MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16subbands for system bandwidth of 1.25, 2.5, 5, 10, or 20 MHz,respectively.

LTE supports a single numerology (subcarrier spacing, symbol length,etc.). In contrast, NR may support multiple numerologies (μ), forexample, subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240kHz or greater may be available. Table 1 provided below lists somevarious parameters for different NR numerologies.

TABLE 1 Max. nominal Subcarrier Symbol system BW spacing slot duration(MHz) with (kHz) Symbols/slot slots/subframe slots/frame (ms) (μs) 4KFFT size 15 14 1 10 1 66.7 50 30 14 2 20 0.5 33.3 100 60 14 4 40 0.2516.7 100 120 14 8 80 0.125 8.33 400 240 14 16 160 0.0625 4.17 800

In the examples of FIGS. 4A to 4D, a numerology of 15 kHz is used. Thus,in the time domain, a frame (e.g., 10 ms) is divided into 10 equallysized subframes of 1 ms each, and each subframe includes one time slot.In FIGS. 4A to 4D, time is represented horizontally (e.g., on the Xaxis) with time increasing from left to right, while frequency isrepresented vertically (e.g., on the Y axis) with frequency increasing(or decreasing) from bottom to top.

A resource grid may be used to represent time slots, each time slotincluding one or more time concurrent resource blocks (RBs) (alsoreferred to as physical RBs (PRBs)) in the frequency domain. Theresource grid is further divided into multiple resource elements (REs).An RE may correspond to one symbol length in the time domain and onesubcarrier in the frequency domain. In the numerology of FIGS. 4A to 4D,for a normal cyclic prefix, an RB may contain 12 consecutive subcarriersin the frequency domain and seven consecutive symbols in the timedomain, for a total of 84 REs. For an extended cyclic prefix, an RB maycontain 12 consecutive subcarriers in the frequency domain and sixconsecutive symbols in the time domain, for a total of 72 REs. Thenumber of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 4A, some of the REs carry downlink reference(pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS mayinclude demodulation reference signals (DMRS), channel state informationreference signals (CSI-RS), cell-specific reference signals (CRS),positioning reference signals (PRS), navigation reference signals (NRS),tracking reference signals (TRS), etc., exemplary locations of which arelabeled “R” in FIG. 4A.

A collection of resource elements that are used for transmission of PRSis referred to as a “PRS resource,” and may be identified by theparameter DL-PRS-ResourceId. The collection of resource elements (REs)can span multiple PRBs in the frequency domain and N (e.g., 1 or more)consecutive symbol(s) within a slot in the time domain. In a given OFDMsymbol in the time domain, a PRS resource occupies consecutive PRBs inthe frequency domain.

A “PRS resource set” is a set of PRS resources used for the transmissionof PRS signals, where each PRS resource has a PRS resource ID(DL-PRS-ResourceId). In addition, the PRS resources in a PRS resourceset are associated with the same TRP. A PRS resource set is identifiedby a PRS resource set ID (DL-PRS-ResourceSetId) and is associated with aparticular TRP (identified by a cell ID). In addition, the PRS resourcesin a PRS resource set have the same periodicity, a common muting patternconfiguration, and the same repetition factor across slots. Theperiodicity may have a length of 2^(μ)·t slots, with t selected from aset of {4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560,5120, 10240}, and μ=0, 1, 2, or 3 (an identifier of the numerology). Therepetition factor may have a length of n slots, with n selected from aset of {1, 2, 4, 6, 8, 16, 32}.

A PRS resource ID in a PRS resource set is associated with a single beam(and/or beam ID) transmitted from a single TRP (where a TRP may transmitone or more beams). That is, each PRS resource of a PRS resource set maybe transmitted on a different beam, and as such, a “PRS resource,” orsimply “resource,” can also be referred to as a “beam.” Note that thisdoes not have any implications on whether the TRPs and the beams onwhich PRS are transmitted are known to the UE.

A “PRS instance” or “PRS occasion” is one instance of a periodicallyrepeated time window (e.g., a group of one or more consecutive slots)where PRS are expected to be transmitted. A PRS occasion may also bereferred to as a “PRS positioning occasion,” a “PRS positioninginstance,” a “positioning occasion,” “a positioning instance,” or simplyan “occasion” or “instance.”

A “positioning frequency layer” is a collection of one or more PRSresource sets across one or more TRPs that have the same subcarrierspacing (SCS) and cyclic prefix (CP) type (meaning all numerologiessupported for the physical downlink shared channel (PDSCH) are alsosupported for PRS), the same Point A, the same value of the downlink PRSbandwidth, the same start PRB (and center frequency), and the same valueof comb-size. The Point A parameter takes the value of the parameterARFCN-ValueNR, where “ARFCN” stands for “absolute radio-frequencychannel number,” and is an identifier/code that specifies a pair ofphysical radio channel used for transmission and reception. The downlinkPRS bandwidth may have a granularity of four PRBs, with a minimum of 24PRBs and a maximum of 272 PRBs. The comb-size indicates the number ofsubcarriers in each symbol carrying PRS. For example, a comb-size ofcomb-4 means that every fourth subcarrier of a given symbol carries PRS.Currently, up to four frequency layers have been defined, and up to twoPRS resource sets may be configured per TRP per frequency layer.

Downlink PRS resource IDs are locally defined within a downlink PRSresource set, and downlink PRS resource set IDs are locally definedwithin a TRP. To uniquely identify a DL-PRS resource across TRPs, an IDhas been defined that can be associated with multiple downlink PRSresource sets associated with a single TRP. This ID can be used alongwith a downlink PRS resource set ID and a downlink PRS resource ID touniquely identify a single downlink PRS resource. This ID is referred toherein as DL-PRS-TRP-ResourceSetId. Each TRP should only be associatedwith one DL-PRS-TRP-ResourceSetId. For example, aDL-PRS-TRP-ResourceSetId may be a cell ID (e.g., PCI, VCI), or a TRP ID,or another identifier that is different than the cell ID or the TRP IDthat is used for positioning purposes to participate in the uniqueidentification of a PRS resource.

Note that the terms “positioning reference signal” and “PRS” maysometimes refer to specific reference signals that are used forpositioning in LTE systems. However, as used herein, unless otherwiseindicated, the terms “positioning reference signal” and “PRS” refer toany type of reference signal that can be used for positioning, such asbut not limited to, PRS signals in LTE, NRS, TRS, CRS, CSI-RS, DMRS,primary synchronization signal (PSS), secondary synchronization signal(SSS), etc.

FIG. 4B illustrates an example of various channels within a downlinkslot of a radio frame. In NR, the channel bandwidth, or systembandwidth, is divided into multiple bandwidth parts (BWPs). A BWP is acontiguous set of PRBs selected from a contiguous subset of the commonRBs for a given numerology on a given carrier. Generally, a maximum offour BWPs can be specified in the downlink and uplink. That is, a UE canbe configured with up to four BWPs on the downlink, and up to four BWPson the uplink. Only one BWP (uplink or downlink) may be active at agiven time, meaning that the UE may only receive or transmit over oneBWP at a time. On the downlink, the bandwidth of each BWP should beequal to or greater than the bandwidth of the SSB, but it may or may notcontain the SSB.

Referring to FIG. 4B, a PSS is used by a UE to determine subframe/symboltiming and a physical layer identity. An SSS is used by a UE todetermine a physical layer cell identity group number and radio frametiming. Based on the physical layer identity and the physical layer cellidentity group number, the UE can determine a PCI. Based on the PCI, theUE can determine the locations of the aforementioned DL-RS. The physicalbroadcast channel (PBCH), which carries an MIB, may be logically groupedwith the PSS and SSS to form an SSB (also referred to as an SS/PBCH).The MIB provides a number of RBs in the downlink system bandwidth and asystem frame number (SFN). The PDSCH carries user data, broadcast systeminformation not transmitted through the PBCH, such as system informationblocks (SIBs), and paging messages.

The physical downlink control channel (PDCCH) carries downlink controlinformation (DCI) within one or more control channel elements (CCEs),each CCE including one or more RE group (REG) bundles (which may spanmultiple symbols in the time domain), each REG bundle including one ormore REGs, each REG corresponding to 12 resource elements (one resourceblock) in the frequency domain and one OFDM symbol in the time domain.The set of physical resources used to carry the PDCCH/DCI is referred toin NR as the control resource set (CORESET). In NR, a PDCCH is confinedto a single CORESET and is transmitted with its own DMRS. This enablesUE-specific beamforming for the PDCCH.

In the example of FIG. 4B, there is one CORESET per BWP, and the CORESETspans three symbols in the time domain. Unlike LTE control channels,which occupy the entire system bandwidth, in NR, PDCCH channels arelocalized to a specific region in the frequency domain (i.e., aCORESET). Thus, the frequency component of the PDCCH shown in FIG. 4B isillustrated as less than a single BWP in the frequency domain. Note thatalthough the illustrated CORESET is contiguous in the frequency domain,it need not be. In addition, the CORESET may span less than threesymbols in the time domain.

The DCI within the PDCCH carries information about uplink resourceallocation (persistent and non-persistent) and descriptions aboutdownlink data transmitted to the UE. Multiple (e.g., up to eight) DCIscan be configured in the PDCCH, and these DCIs can have one of multipleformats. For example, there are different DCI formats for uplinkscheduling, for non-MIMO downlink scheduling, for MIMO downlinkscheduling, and for uplink power control. A PDCCH may be transported by1, 2, 4, 8, or 16 CCEs in order to accommodate different DCI payloadsizes or coding rates.

As illustrated in FIG. 4C, some of the REs carry DMRS for channelestimation at the base station. The UE may additionally transmitsounding reference signals (SRS) in, for example, the last symbol of asubframe. The SRS may have a comb structure, and a UE may transmit SRSon one of the combs. The comb structure (also referred to as the “combsize”) indicates the number of subcarriers in each symbol periodcarrying a reference signal (here, SRS). For example, a comb size ofcomb-4 means that every fourth subcarrier of a given symbol carries thereference signal, whereas a comb size of comb-2 means that every secondsubcarrier of a given symbol carries the reference signal. In theexample of FIG. 4C, the illustrated SRS (e.g., SRS #0 and SRS #1) areboth comb-2. The SRS may be used by a base station to obtain the channelstate information (CSI) for each UE. CSI describes how an RF signalpropagates from the UE to the base station and represents the combinedeffect of scattering, fading, and power decay with distance. The systemuses the SRS for resource scheduling, link adaptation, massive MIMO,beam management, etc.

FIG. 4D illustrates an example of various channels within an uplinksubframe of a frame, according to aspects of the disclosure. A randomaccess channel (RACH), also referred to as a physical random accesschannel (PRACH), may be within one or more subframes within a framebased on the PRACH configuration. The PRACH may include six consecutiveRB pairs within a subframe. The PRACH allows the UE to perform initialsystem access and achieve uplink synchronization. A physical uplinkcontrol channel (PUCCH) may be located on edges of the uplink systembandwidth. The PUCCH carries uplink control information (UCI), such asscheduling requests, CSI reports, a channel quality indicator (CQI), aprecoding matrix indicator (PMI), a rank indicator (RI), and HARQACK/NACK feedback. The physical uplink shared channel (PUSCH) carriesdata, and may additionally be used to carry a buffer status report(BSR), a power headroom report (PHR), and/or UCI.

A collection of resource elements that are used for transmission of SRSis referred to as an “SRS resource,” and may be identified by theparameter SRS-ResourceId. The collection of resource elements can spanmultiple PRBs in the frequency domain and N (e.g., one or more)consecutive symbol(s) within a slot in the time domain. In a given OFDMsymbol, an SRS resource occupies consecutive PRBs. An “SRS resource set”is a set of SRS resources used for the transmission of SRS signals, andis identified by an SRS resource set ID (SRS-ResourceSetId).

Generally, a UE transmits SRS to enable the receiving base station(either the serving base station or a neighboring base station) tomeasure the channel quality between the UE and the base station.However, SRS can also be used as uplink positioning reference signalsfor uplink positioning procedures, such as uplink time-difference ofarrival (UTDOA), multi-round-trip-time (multi-RTT), uplinkangle-of-arrival (UL-AoA), etc.

FIG. 5A illustrates an exemplary four-step random access procedure 500A,according to aspects of the disclosure. The four-step random accessprocedure 500A is performed between a UE 504 and a base station 502,which may correspond to any of the UEs and base stations, respectively,described herein.

There are various situations in which a UE may perform the four-steprandom access procedure 500A (also referred to as a “RACH procedure,” a“PRACH procedure,” and the like). For example, a UE may perform thefour-step random access procedure 500A when acquiring initial networkaccess after coming out of the RRC idle state, when performing an RRCconnection re-establishment procedure, during a handover, when downlinkor uplink data arrives and the UE is in an RRC connected state but itsuplink synchronization status is “not-synchronized,” when transitioningout of the RRC INACTIVE state, when establishing time alignment for theaddition of an SCell, when requesting other synchronization information,or when performing beam failure recovery.

Before performing the four-step random access procedure 500A, the UE 504first reads one or more SSBs broadcasted by the base station 502 withwhich the UE 504 is performing the four-step random access procedure500A. In NR, each beam transmitted by a base station (e.g., base station502) is associated with a different SSB, and a UE (e.g., UE 504) selectsa certain beam to use to communicate with the base station 502. Based onthe SSB of the selected beam, the UE 504 can then read the SIB type 1(SIB1), which carries cell access related information and supplies theUE 504 with the scheduling of other system information blockstransmitted on the selected beam.

When the UE sends the very first message of the four-step random accessprocedure 500A to the base station 502, it sends a specific patterncalled a preamble (also referred to as a RACH preamble, a PRACHpreamble, a preamble sequence, or a sequence). The RACH preambledifferentiates requests from different UEs 504. However, if two UEs 504use the same RACH preamble at the same time, then there can be acollision. There are a total of 64 such patterns available to a UE 504,and, for contention-based random access, the UE 504 chooses one of themrandomly. For contention-free random access, however, the networkinstructs the UE 504 about which one to use.

At 510, the UE 504 selects one of 64 RACH preambles to send to the basestation 502 as a RACH request. This message is referred to as “Message1” or “Msg1” in a four-step RACH procedure. Based on the synchronizationinformation from the base station 502 (i.e., the SIB1), the UE 504selects a RACH preamble and sends it at the RACH occasion (RO)corresponding to the selected SSB/beam. More specifically, in order forthe base station 502 to determine which beam the UE 504 has selected, aspecific mapping is defined between an SSB and an RO (which occur every10, 20, 40, 80, or 160 ms). By detecting at which RO the UE 504 sent thepreamble, the base station 502 can determine which SSB/beam the UE 504selected.

Note that an RO is a time-frequency transmission opportunity fortransmitting a RACH preamble, and a RACH preamble index (i.e., a valuefrom 0 to 63 for the 64 possible preambles) enables the UE 504 togenerate the type of RACH preamble expected at the base station 502. TheRO and RACH preamble index may be configured to the UE 504 by the basestation 502 in a SIB. A RACH resource is an RO in which one RACHpreamble index is transmitted. As such, the terms “RO” (or “RACHoccasion”) and “RACH resource” may be used interchangeably, depending onthe context.

Due to reciprocity, the UE 504 may use the uplink transmit beamcorresponding to the best downlink receive beam determined duringsynchronization (i.e., the best receive beam to receive the selecteddownlink beam from the base station 502). That is, the UE 504 uses theparameters of the downlink receive beam used to receive the beam fromthe base station 502 to determine the parameters of the uplink transmitbeam. If reciprocity is available at the base station 502, the UE 504can transmit the preamble over one beam. Otherwise, the UE 504 repeatstransmission of the same preamble on all of its uplink transmit beams.

The UE 504 also needs to provide its identity to the network (via basestation 502) so that the network can address it in the next step. Thisidentity is called the random access radio network temporary identity(RA-RNTI) and is determined from the time slot in which the RACHpreamble is sent. If the UE 504 does not receive any response from thebase station 502 within some period of time, it increases itstransmission power in a fixed step and sends the RACH preamble/Msg1again.

At 520, the base station 502 sends a random access response (RAR),referred to as a “Message 2” or “Msg2” in a four-step RACH procedure, tothe UE 504 on the selected beam. The RAR is sent on a PDSCH and isaddressed to the RA-RNTI calculated from the time slot (i.e., RO) inwhich the preamble was sent. The RAR carries the following information:a cell-radio network temporary identifier (C-RNTI), a timing advance(TA) value, and an uplink grant resource. The base station 502 assignsthe C-RNTI to the UE 504 to enable further communication with the UE504. The TA value specifies how much the UE 504 should change its timingto compensate for the round-trip delay between the UE 504 and the basestation 502. The uplink grant resource indicates the initial resourcesthe UE 504 can use on the PUSCH. After this step, the UE 504 and thebase station 502 establish coarse beam alignment that can be utilized inthe subsequent steps.

At 530, using the allocated PUSCH, the UE 504 sends an RRC connectionrequest message, referred to as a “Message 3” or “Msg3,” to the basestation 502. Because the UE 504 sends the Msg3 over the resourcesscheduled by the base station 502, the base station 502 therefore knowswhere to detect the Msg3 and which uplink receive beam should be used.Note that the Msg3 PUSCH can be sent on the same or different uplinktransmit beam than the Msg1.

The UE 504 identifies itself in the Msg3 by the C-RNTI assigned in theprevious step. The message contains the UE's 504 identity and connectionestablishment cause. The UE's 504 identity is either a temporary mobilesubscriber identity (TMSI) or a random value. A TMSI is used if the UE504 has previously connected to the same network. The UE 504 isidentified in the core network by the TMSI. A random value is used ifthe UE 504 is connecting to the network for the very first time. Thereason for the random value or TMSI is that the C-RNTI may have beenassigned to more than one UE in the previous step, due to multiplerequests arriving at the same time. The connection establishment causeindicates the reason why the UE 504 needs to connect to the network, andwill be described further below.

At 540, if the Msg3 was successfully received, the base station 502responds with a contention resolution message, referred to as a “Message4” or “Msg4.” This message is addressed to the TMSI or random value(from the Msg3) but contains a new C-RNTI that will be used for furthercommunication. Specifically, the base station 502 sends the Msg4 in thePDSCH using the downlink transmit beam determined in the previous step.

The four-step random access procedure 500A described above is acontention-based random access procedure. In contention-based randomaccess, any UE 504 connecting to the same cell or TRP sends the samerequest, in which case there is a possibility of collision among therequests from the various UEs 504. In contention-free random access, thenetwork can instruct a UE 504 to use some unique identity to prevent itsrequest from colliding with requests from other UEs. A contention-freerandom access procedure can be performed when the UE 504 is in an RRCconnected mode before the random access procedure, such as in the caseof a handover.

FIG. 5B illustrates an exemplary two-step random access procedure 500B,according to aspects of the disclosure. The two-step random accessprocedure 500B is performed between the UE 504 and the base station 502.

At 550, the UE 504 transmits a RACH Message A (“MsgA”) to the basestation 502. In a two-step random access procedure 500B, Msg1 and Msg3,described above with reference to FIG. 5A, are collapsed (e.g.,combined) into MsgA and sent to the base station 502. As such, a MsgAincludes a RACH preamble and a PUSCH, similar to the Msg3 PUSCH of afour-step RACH procedure. The RACH preamble may have been selected from64 possible preambles, as described above with reference to FIG. 5A, andmay be used as a reference signal for demodulation of the datatransmitted in the MsgA. At 560, the UE 504 receives a RACH Message B(“MsgB”) from the base station 502. The MsgB may be a combination ofMsg2 and Msg4 described above with reference to FIG. 5A.

The combination of Msg1 and Msg3 into one MsgA and the combination ofMsg2 and Msg4 into one MsgB allows the UE 504 to reduce the RACHprocedure setup time to support the low-latency requirements of 5G NR.Although the UE 504 may be configured to support the two-step randomaccess procedure 500B, the UE 504 may still support the four-step randomaccess procedure 500A as a fall back if the UE 504 is not be able to usethe two-step random access procedure 500B due to some constraints (e.g.,high transmit power requirements, etc.). Therefore, a UE in 5G NR may beconfigured to support both the two-step and the four-step random accessprocedures, and may determine which random access procedure to configurebased on the RACH configuration information received from the basestation.

After the random access procedure 500A or 500B, the UE 504 is in an RRCconnected state. The RRC protocol is used on the air interface betweenthe UE 504 and the base station 502.

Due to UE mobility/movement, beam reconfiguration at the base station,and/or other factors, a downlink beam (e.g., comprising a downlinkcontrol link), which may have been the preferred active beam, may failto be detected at the UE, or the signal quality (e.g., RSRP, RSRQ, SINR,etc.) may fall below a threshold, causing the UE to consider it as abeam/link failure. A beam recovery procedure may be employed to recoverfrom such a beam failure. A beam failure may refer to, for example,failure to detect a strong (e.g., with signal power greater than athreshold) active beam, which may, in some aspects, correspond to acontrol channel communicating control information from the network. Incertain aspects, in order to facilitate beam failure detection, a UE maybe preconfigured with beam identifiers (IDs) of a first set of beams(referred to as “set_q0”) to be monitored, a monitoring period, a signalstrength threshold, etc. The recovery may be triggered when a signalstrength (e.g., RSRP, RSRQ, SINR, etc.) associated with the one or moremonitored beams (as detected by the UE) falls below a threshold. Therecovery process may include the UE identifying a new beam, for example,from a second set of possible beams (corresponding to beam IDs that maybe included in a second set, referred to as “set_q1”), and performing arandom access procedure (e.g., as illustrated in FIGS. 5A and 5B) usingpreconfigured time and frequency resources corresponding to the newpreferred beam. The beam IDs corresponding to the beams in the secondset of beams (set_q1) may be preconfigured at the UE for use for beamfailure recovery purposes. For example, the UE may monitor downlinkbeams (based on the beam IDs and resources identified in the secondset), perform measurements, and determine (e.g., based on themeasurements) which beam out of all received and measured beams may bethe best for reception at the UE from the UE's perspective.

If beam correspondence is assumed (i.e., the direction of the bestreceive beam used by the UE is also considered the best direction forthe transmit beam used by the UE), then the UE may assume the same beamconfiguration for both reception and transmission. That is, based onmonitoring downlink reference signals from the base station, the UE candetermine its preferred uplink transmit beam weights, which will be thesame as for the downlink receive beam used for receiving the downlinkreference signals.

Where beam correspondence is not assumed (e.g., deemed not suitable inthe given scenario or for other reasons), the UE may not derive theuplink transmit beam from the downlink receive beam. Instead, separatesignaling is needed to select the uplink transmit and downlink receivebeam weights and for the UL-to-DL beam pairing. The UE may perform aRACH procedure (e.g., using the preconfigured time and frequencyresources indicated in the second set of beams, set_q1) to identify theuplink transmit beam. Performing the RACH procedure using thepreconfigured time and frequency resources may comprise, for example,transmitting a RACH preamble on one or more uplink transmit beams(corresponding to the beam IDs in the second set of beams, set_q1) onallocated RACH resources corresponding to the one or more beams. Basedon the RACH procedure, the UE may be able to determine and confirm withthe base station which uplink direction may be the best beam directionfor an uplink channel (e.g., PUCCH). In this manner, both uplinktransmit and downlink receive beams may be reestablished and beamrecovery may be completed.

FIG. 6 is a diagram 600 of an exemplary RACH-based SpCell beam failurerecovery procedure, according to aspects of the disclosure. In theexample of FIG. 6, for simplicity, the PCell and SCell are shown to beassociated with a single base station (e.g., the hardware/circuitry forimplementing the PCell and SCell may be collocated at the same basestation). However, in some other configurations, the PCell and SCell maybe associated with different base stations that may be synchronized.

In the example of FIG. 6, a PCell or a primary (i.e., in active use)SCell (together referred to as an “SpCell”) is supported by a basestation 602 (illustrated as a “gNB,” and which may correspond to any ofthe base stations described herein). A UE 604 (which may correspond toany of the UEs described herein) monitors the received signal strength(e.g., RSRP, RSRQ, SINR, etc.) of periodic reference signals (e.g., PRS)transmitted by the base station 602 on a first set (“set_q0”) ofdownlink transmit beams 606 of the SpCell. The first set of downlinktransmit beams 606 is referred to as the “failure detection resourceset” because the base station 602 sends the beam IDs of the beams in thefirst set of downlink transmit beams 606 to the UE 604 to enable the UE604 to monitor these beams to determine whether or not the downlinkcontrol link (i.e., a control channel communicating control informationfrom the network) between the base station 602 and the UE 604 is active.In the example of FIG. 6, the first set of downlink transmit beams 606includes two beams. However, there may be only one beam or more than twobeams in the first set of downlink transmit beams 606.

At 610, the UE 604 fails to detect a periodic reference signaltransmitted on at least one of the beams in the first set of downlinktransmit beams 606, and/or detects that a quality metric (e.g., RSRP,RSRQ, SINR, etc.) associated with the reference signal has fallen belowa signal quality threshold (represented in FIG. 6 as “Qout”). The Qoutthreshold may be configured by the base station 602. More specifically,the Layer 1 (“L1” in FIG. 6) functionality of the UE 604 (e.g.,implemented in the WWAN transceiver 310) detects that the measuredquality metric of the periodic reference signal is below the Qoutthreshold, and sends an out-of-sync (OOS) indication to the processingsystem 332 (which implements the Layer 2 and Layer 3 functionality ofthe UE 604). In response to receiving the OOS indication, the processingsystem 332 of the UE 604 starts a beam failure detection (BFD) timer andinitializes a beam failure indicator (BFI) counter to “1.”

At 615, the UE 604 again fails to detect the periodic reference signaltransmitted on the at least one of the beams in the first set ofdownlink transmit beams 606, and/or again detects that the qualitymetric associated with the reference signal has fallen below the Qoutthreshold. Again, more specifically, the Layer 1 functionality of the UE604 detects that the measured quality metric of the periodic referencesignal is below the Qout threshold, and sends another OOS indication tothe processing system 332. The processing system 332 increments the BFIcount to “2.” Because the BFI count has reached the maximum count(“MaxCnt”) threshold (which is “2” in the example of FIG. 6 but whichmay be another value) while the BFD timer is running, the UE 604determines that there has been a beam failure of the at least one beam(e.g., a downlink control beam) in the first set of downlink transmitbeams 606. Because there is a failure of a downlink control beam(corresponding to the downlink control channel communicating controlinformation from the network), the UE 604 assumes that there is also afailure of the corresponding uplink control beam (corresponding to theuplink control channel for communicating control information to thenetwork). As such, the UE 604 needs to identify a new downlink controlbeam and re-establish an uplink control beam. The UE 604 also resets theBFD timer.

Thus, at 620, in response to the beam failure detection at 615, the UE604 initiates a beam failure recovery procedure. More specifically, theprocessing system 332 of the UE 604 requests that the Layer 1functionality of the UE 604 identify at least one beam in a second set(“set_q1”) of downlink transmit beams 608 that carries a periodicreference signal with a received signal strength greater than a signalquality threshold (represented as “Qin”). The second set of downlinktransmit beams 608 is referred to as the “candidate beam referencesignal list.” The UE 604 may receive both the beam IDs of the beams inthe second set of downlink transmit beams 608 and the Qin threshold fromthe base station 602. In the example of FIG. 6, the second set ofdownlink transmit beams 608 includes four beams, one of which (shaded)carries periodic reference signals having a received signal strengthgreater than the Qin threshold. However, as will be appreciated, theremay be more or fewer than four beams in the second set of downlinktransmit beams 608, and there may be more than one beam that meets theQin threshold. The WWAN transceiver 310 (implementing Layer 1functionality) reports the identified candidate beam to the processingsystem 332. The identified candidate beam can then be used as the newdownlink control beam, although not necessarily immediately.

At 625, to re-establish an uplink control beam, the UE 604 performs aRACH procedure (e.g., as illustrated in FIGS. 5A and 5B) on the one ormore candidate downlink transmit beams identified at 620 (one in theexample of FIG. 6). More specifically, the processing system 332instructs the WWAN transceiver 310 to send a RACH preamble (which may bepre-stored or provided to the UE 604 by the base station 602) to thebase station 602. The WWAN transceiver 310 sends the RACH preamble (alsoreferred to as a Message 1 (“Msg1”)) on one or more candidate uplinktransmit beams corresponding to the one or more candidate downlinktransmit beams identified at 620 on preconfigured RACH resources for theone or more candidate uplink transmit beams. The preconfigured RACHresources may correspond to the SpCell (e.g., in the mmW band). Althoughnot illustrated in FIG. 6, at 625, the UE 604 also starts a beam failurerecovery (BFR) timer that defines a contention-free random access (CFRA)response window.

The one or more candidate downlink transmit beams identified at 620 caninclude beams that are different than the downlink transmit beamassociated with the beam failure. As used herein, a “beam” is defined bybeam weights associated with an antenna array of the UE 604. Hence, insome aspects, whether used for uplink transmission by the UE 604 ordownlink reception by the UE 604, the weights applied to each antenna inthe array to construct the transmitted or received beam define the beam.As such, the one or more candidate uplink transmit beams on which theRACH preamble is sent may have different weights than the downlinktransmit beam associated with the beam failure, even if such candidateuplink transmit beam is in generally a similar direction as the downlinktransmit beam indicated to be failing.

At 630, the base station 602 transmits a RACH response (referred to as a“Msg1 response”) to the UE 604 with a C-RNTI via a PDCCH associated withthe SpCell. For example, the response may comprise cyclic redundancycheck (CRC) bits scrambled by the C-RNTI. After the WWAN transceiver 310of the UE 604 processes the received response with the C-RNTI via theSpCell PDCCH from the base station 602 and determines that the receivedPDCCH is addressed to the C-RNTI, the processing system 332 determinesthat the beam failure recovery procedure has completed and stops the BFRtimer started at 625. In an aspect, the C-RNTI may be mapped to a beamdirection determined by the base station 602 to be the best directionfor an uplink channel (e.g., PUCCH) for the UE 604. Accordingly, uponreceipt of the response with C-RNTI from the base station 602, the UE604 may be able to determine the optimal uplink transmit beam that isbest suited for the uplink channel.

The operations at 630 are part of a first scenario in which the UE 604successfully recovers from the beam failure detected at 615. However,such a recovery may not always occur, or at least not before the BFRtimer started at 625 times out. If the BFR timer expires before the beamfailure recovery procedure completes successfully, then at 635, the UE604 determines that a radio link failure (RLF) has occurred.

FIG. 7 illustrates an exemplary wireless communications system 700according to various aspects of the disclosure. In the example of FIG.7, a UE 704, which may correspond to any of the UEs described herein, isattempting to calculate an estimate of its position, or assist anotherentity (e.g., a base station or core network component, another UE, alocation server, a third party application, etc.) to calculate anestimate of its position. The UE 704 may communicate wirelessly with aplurality of base stations 702-1, 702-2, and 702-3 (collectively, basestations 702), which may correspond to any combination of the basestations described herein, using RF signals and standardized protocolsfor the modulation of the RF signals and the exchange of informationpackets. By extracting different types of information from the exchangedRF signals, and utilizing the layout of the wireless communicationssystem 700 (e.g., the base stations locations, geometry, etc.), the UE704 may determine its position, or assist in the determination of itsposition, in a predefined reference coordinate system. In an aspect, theUE 704 may specify its position using a two-dimensional (2D) coordinatesystem; however, the aspects disclosed herein are not so limited, andmay also be applicable to determining positions using athree-dimensional (3D) coordinate system, if the extra dimension isdesired. Additionally, while FIG. 7 illustrates one UE 704 and threebase stations 702, as will be appreciated, there may be more UEs 704 andmore or fewer base stations 702.

To support position estimates, the base stations 702 may be configuredto broadcast positioning reference signals (e.g., PRS, NRS, TRS, CRS,etc.) to UEs 704 in their coverage area to enable a UE 704 to measurecharacteristics of such reference signals. For example, the OTDOApositioning method, also referred to as the time difference of arrival(TDOA) positioning method, is a multilateration method in which the UE704 measures the time difference, known as a RSTD, between specificreference signals (e.g., PRS, NRS, TRS, CRS, etc.) transmitted bydifferent pairs of network nodes (e.g., base stations 702, antennas ofbase stations 702, etc.) and either reports these time differences to alocation server, such as the location server 230 or LMF 270, or computesa location estimate itself from these time differences.

Generally, RSTDs are measured between a reference network node (e.g.,base station 702-1 in the example of FIG. 7) and one or more neighbornetwork nodes (e.g., base stations 702-2 and 702-3 in the example ofFIG. 7). The reference network node remains the same for all RSTDsmeasured by the UE 704 for any single positioning use of OTDOA and wouldtypically correspond to the serving cell for the UE 704 or anothernearby cell with good signal strength at the UE 704. In an aspect, wherea measured network node is a cell supported by a base station, theneighbor network nodes would normally be cells supported by basestations different from the base station for the reference cell and mayhave good or poor signal strength at the UE 704. The locationcomputation can be based on the measured time differences (e.g., RSTDs)and knowledge of the network nodes' locations and relative transmissiontiming (e.g., regarding whether network nodes are accuratelysynchronized or whether each network node transmits with some known timedifference relative to other network nodes).

To assist positioning operations, a location server (e.g., locationserver 230, LMF 270) may provide OTDOA assistance data to the UE 704 forthe reference network node (e.g., base station 702-1 in the example ofFIG. 7) and the neighbor network nodes (e.g., base stations 702-2 and702-3 in the example of FIG. 7) relative to the reference network node.For example, the assistance data may provide the center channelfrequency of each network node, various reference signal configurationparameters (e.g., the number of consecutive positioning subframes,periodicity of positioning subframes, muting sequence, frequency hoppingsequence, reference signal identifier (ID), reference signal bandwidth),a network node global ID, and/or other cell related parametersapplicable to OTDOA. The OTDOA assistance data may indicate the servingcell for the UE 704 as the reference network node.

In some cases, OTDOA assistance data may also include “expected RSTD”parameters, which provide the UE 704 with information about the RSTDvalues the UE 704 is expected to measure at its current location betweenthe reference network node and each neighbor network node, together withan uncertainty of the expected RSTD parameter. The expected RSTD,together with the associated uncertainty, may define a search window forthe UE 704 within which the UE 704 is expected to measure the RSTDvalue. OTDOA assistance information may also include reference signalconfiguration information parameters, which allow a UE 704 to determinewhen a reference signal positioning occasion occurs on signals receivedfrom various neighbor network nodes relative to reference signalpositioning occasions for the reference network node, and to determinethe reference signal sequence transmitted from various network nodes inorder to measure a signal time of arrival (ToA) or RSTD.

In an aspect, while the location server (e.g., location server 230, LMF270) may send the assistance data to the UE 704, alternatively, theassistance data can originate directly from the network nodes (e.g.,base stations 702) themselves (e.g., in periodically broadcastedoverhead messages, etc.). Alternatively, the UE 704 can detect neighbornetwork nodes itself without the use of assistance data.

The UE 704 (e.g., based in part on the assistance data, if provided) canmeasure and (optionally) report the RSTDs between reference signalsreceived from pairs of network nodes. Using the RSTD measurements, theknown absolute or relative transmission timing of each network node, andthe known position(s) of the transmitting antennas for the reference andneighboring network nodes, the network (e.g., location server 230/LMF270, a base station 702) or the UE 704 may estimate a position of the UE704. More particularly, the RSTD for a neighbor network node “k”relative to a reference network node “Ref” may be given as(ToA_(k)−ToA_(Ref)), where the ToA values may be measured modulo onesubframe duration (1 ms) to remove the effects of measuring differentsubframes at different times. In the example of FIG. 7, the measuredtime differences between the reference cell of base station 702-1 andthe cells of neighboring base stations 702-2 and 702-3 are representedas t₂−t₁ and t₃−t₁, where t₁, t₂, and t₃ represent the ToA of areference signal from the transmitting antenna(s) of base stations702-1, 702-2, and 702-3, respectively. The UE 704 may then convert theToA measurements for different network nodes to RSTD measurements and(optionally) send them to the location server 230/LMF 270. Using (i) theRSTD measurements, (ii) the known absolute or relative transmissiontiming of each network node, (iii) the known position(s) of physicaltransmitting antennas for the reference and neighboring network nodes,and/or (iv) directional reference signal characteristics such as adirection of transmission, the UE's 704 position may be determined(either by the UE 704 or the location server 230/LMF 270).

Still referring to FIG. 7, when the UE 704 obtains a location estimateusing OTDOA measured time differences, the necessary additional data(e.g., the network nodes' locations and relative transmission timing)may be provided to the UE 704 by a location server (e.g., locationserver 230, LMF 270). In some implementations, a location estimate forthe UE 704 may be obtained (e.g., by the UE 704 itself or by thelocation server 230/LMF 270) from OTDOA measured time differences andfrom other measurements made by the UE 704 (e.g., measurements of signaltiming from GPS or other global navigation satellite system (GNSS)satellites). In these implementations, known as hybrid positioning, theOTDOA measurements may contribute towards obtaining the UE's 704location estimate but may not wholly determine the location estimate.

UTDOA is a similar positioning method to OTDOA, but is based on uplinkreference signals (e.g., SRS, uplink PRS) transmitted by the UE (e.g.,UE 704). Further, transmission and/or reception beamforming at the basestation 702 and/or UE 704 can enable wideband bandwidth at the cell edgefor increased precision. Beam refinements may also leverage channelreciprocity procedures in 5G NR.

Another uplink positioning procedure is UL-AOA. In UL-AoA positioning,the base station uses the angle and other properties (e.g., signalstrength) of the uplink receive beam on which it receives referencesignals (e.g., SRS) to estimate the location of the UE. The basestation, or other positioning entity, may also use the signalpropagation time between the base station and the UE to determine thedistance between the base station and the UE to further refine thelocation estimate of the UE. The signal propagation time, or flighttime, may be determined using multi-RTT.

The term “position estimate” is used herein to refer to an estimate of aposition for a UE, which may be geographic (e.g., may comprise alatitude, longitude, and possibly altitude) or civic (e.g., may comprisea street address, building designation, or precise point or area withinor nearby to a building or street address, such as a particular entranceto a building, a particular room or suite in a building, or a landmarksuch as a town square). A position estimate may also be referred to as a“location,” a “position,” a “fix,” a “position fix,” a “location fix,” a“location estimate,” a “fix estimate,” or by some other term. The meansof obtaining a location estimate may be referred to generically as“positioning,” “locating,” or “position fixing.” A particular solutionfor obtaining a position estimate may be referred to as a “positionsolution.” A particular method for obtaining a position estimate as partof a position solution may be referred to as a “position method” or as a“positioning method.”

As noted above, an “RF signal” comprises an electromagnetic wave thattransports information through the space between a transmitter and areceiver. An RF signal typically suffers from some amount of path loss,or path attenuation, which is the reduction in power density(attenuation) of an electromagnetic wave (the RF signal) as itpropagates through space. Path loss may be due to many effects, such asfree-space loss, refraction, diffraction, reflection, aperture-mediumcoupling loss, and absorption. Path loss is also influenced by terraincontours, environment (e.g., urban or rural, vegetation and foliage,etc.), propagation medium (e.g., dry or moist air), the distance betweenthe transmitter and the receiver, and the height and location of thetransmit antenna(s).

A transmitter (e.g., a base station or a UE) may transmit a single RFsignal or multiple RF signals to a receiver (e.g., a UE or a basestation). However, the receiver may receive multiple RF signalscorresponding to each transmitted RF signal due to the propagationcharacteristics of RF signals through multipath channels. The sametransmitted RF signal on different paths between the transmitter andreceiver may be referred to as a “multipath” RF signal. Multipath RFsignals combine at the receiver, resulting in a received signal that mayvary widely, depending on the distribution of the intensity and relativepropagation time of the waves and bandwidth of the transmitted signal.

As noted above, during UTDOA positioning procedures (and other uplink oruplink-plus-downlink positioning procedures, such as multi-RTT andUL-AoA), a UE transmits uplink reference signals, such as SRS and uplinkPRS, that need to be transmitted with a high enough transmit power thatthey can be measured by neighboring cells. Because neighboring cells maybe further away from the UE than the serving cell, there may be morepath loss between the UE and the neighboring cell than between the UEand the serving cell. As such, these uplink reference signals may needto be transmitted with a higher transmit power than uplink signalstransmitted to the serving cell.

Several options have been identified for setting the transmission powerof uplink reference signals transmitted for positioning purposes (e.g.,UTDOA). As a first option, the transmit power of such uplink referencesignals may be constant (i.e., no power control is supported). As asecond option, the transmit power of uplink reference signals may bebased on the existing power control procedure. As a third option, thetransmit power may be determined by modifying the existing power controlprocedure. For example, a downlink reference signal of a neighboringcell can be configured to be used for the path loss estimation for anuplink reference signal. More specifically, the UE can estimate the pathloss of the downlink reference signal and determine the appropriatetransmit power for the uplink reference signal based on the determinedpath loss. In an aspect, the downlink reference signals may be a CSI-RS,an SSB, a downlink PRS, etc.

Referring to the third option, using a downlink reference signal from aneighboring cell to estimate the path loss of an uplink referencesignal, various other features need to be supported in 5G NR in additionto the existing legacy behaviour. For example, there needs to be supportfor configuring a downlink reference signal of a neighboring cell to beused as the downlink path loss reference for the purposes of uplinkreference signal power control. However, there is no fall back procedurecurrently specified if the UE is not able to obtain the path lossreference. Accordingly, the present disclosure describes various fallback procedures if the UE is not able to obtain the path loss reference.

In addition to using a downlink reference signal to determine thetransmit power of an uplink reference signal, a UE can use a downlinkreference signal from a neighboring cell to determine the spatialdirection of an uplink transmit beam (also referred to as spatialtransmit QCL, spatial QCL, spatial transmit beam, and the like) carryinguplink reference signals (again in the case of a positioning procedure).The downlink reference signal to determine the transmit power of anuplink reference signal and the downlink reference signal to determinethe spatial direction of an uplink transmit beam may be, but need notbe, the same downlink reference signal. For uplink beammanagement/alignment towards the serving and neighboring cells, variousfeatures (in addition to UE transmit beam sweeping) are currentlysupported. First, the configuration of a spatial relation between adownlink reference signal from the serving cell or neighboring cell(s)and the target uplink reference signal is supported. Downlink referencesignals that can be used include at least an SSB, and possibly CSI-RSand PRS. Second, a fixed transmit beam for uplink reference signaltransmissions across multiple uplink reference signal resources, forboth FR1 and FR2, is supported. Note that currently, a UE is notexpected to transmit multiple uplink reference signal resources withdifferent spatial relations in the same OFDM symbol.

As noted above, the UE can calculate the transmit power for an uplinkreference signal based on the path loss of a downlink reference signal.The UE can do so as follows. If a UE transmits uplink reference signals(e.g., SRS) on uplink BWP b of carrier f of serving cell c using an SRSpower control adjustment state with index l, the UE determines the SRStransmission power P_(SRS,b,f,c)(i,q_(s),l) in SRS transmission occasioni as (in dBm):

${P_{{SRS},b,f,c}( {i,q_{S},l} )} = {\min\begin{Bmatrix}P_{{CMAX},f,{c(i)},} \\\begin{matrix}{{P_{{O\_{SRS}},b,f,c}( q_{s} )} + {10{\log_{10}( {2^{u} \times {M_{{SRS},b,f,c}(i)}} )}} +} \\{{{a_{{SRS},b,f,c}( q_{s} )} \times {{PL}_{b,f,c}( q_{a} )}} + {h_{b,f,c}( {i,l} )}}\end{matrix}\end{Bmatrix}}$

where:

-   -   P_(CMAX,f,c)(i) is the configured UE transmit power for carrier        f of serving cell c in SRS transmission occasion i;    -   P_(O_SRS,b,f,c)(q_(s)) is provided by higher layer parameter p0        for uplink BWP b of carrier f of serving cell c and SRS resource        set q_(s) provided by higher layer parameters SRS-ResourceSet        and SRS-ResourceSetId. If p0 is not provided,        P_(O_SRS,b,f,c)(q_(s))=P_(O_NOMINALPUSCH,f,c)(0);    -   M_(SRS,b,f,c)(i) is the SRS bandwidth expressed in number of        resource blocks for SRS transmission occasion i on active uplink        BWP b of carrier f of serving cell c and μ is a SCS        configuration;    -   a_(SRS,b,f,c)(q_(s)) is provided by higher layer parameter alpha        for uplink BWP b of carrier f of serving cell c and SRS resource        set q_(s);    -   PL_(b,f,c)(q_(d)) is a downlink path loss estimate in dB        calculated by the UE using reference signal index q_(d) for a        downlink BWP that is linked with uplink BWP b of carrier f of        serving cell c and SRS resource set q_(s). The reference signal        index q_(d) is provided by the higher layer parameter        pathlossReferenceRS associated with the SRS resource set q_(s)        and is either a higher layer parameter ssb-Index providing an        SS/PBCH block index or a higher layer parameter csi-RS-Index        providing a CSI-RS resource index. If the UE is not provided the        higher layer parameter pathlossReferenceRS or before the UE is        provided dedicated higher layer parameters, the UE calculates        PL_(b,f,c)(q_(d)) using a reference signal resource obtained        from the SS/PBCH block index that the UE uses to obtain the MIB.        If the UE is provided pathlossReferenceLinking, the reference        signal resource is on a serving cell indicated by a value of        pathlossReferenceLinking;    -   h_(b,f,c)(i, l)=f_(b,f,c)(i, l), where f_(b,f,c)(i, l) is the        current PUSCH power control adjustment state, if the higher        layer parameter srs-PowerControlAdjustmentStates indicates the        same power control adjustment state for SRS transmissions and        PUSCH transmissions.

As noted above, a maximum of four BWPs can be specified in the downlinkand uplink. Currently, there may be up to four path loss estimates perserving cell, one for each BWP. Specifically, a UE does not expect tosimultaneously maintain more than four path loss estimates per servingcell for all PUSCH/PUCCH/SRS transmissions. The pathlossReferenceLinkingparameter indicates whether the UE shall apply as path loss referenceeither the downlink of the PCell or the SCell that corresponds with thisuplink.

As noted above, some wireless communications networks, such as 5G NR,may employ mmW or near mmW frequencies to increase the network capacity.The use of mmW frequencies may be in addition to microwave frequencies(e.g., in the sub-6 GHz band) that may also be supported for use incommunication, e.g., when carrier aggregation is used. Becausecommunication at high mmW frequencies utilizes directionality (e.g.,communication via directional beams) to compensate for higherpropagation loss, a base station and a UE may need to align their beamsduring both initial network access (e.g., a random access procedure, asillustrated in FIGS. 5A and 5B) and subsequent data transmissions toensure maximum gain. The base station and the UE may determine the bestbeams for communicating with each other, and the subsequentcommunications between the base station and the UE may be via theselected beams. However, due to UE mobility/movement, beamreconfiguration at the base station, and/or other factors, a downlinkbeam (e.g., comprising a downlink control link), which may have been thepreferred active beam, may fail to be detected at the UE, or the signalquality may fall below a threshold, causing the UE to consider it as abeam/link failure.

A beam recovery procedure (e.g., as illustrated in FIG. 6) may beemployed to recover from a beam failure. A beam failure may refer to,for example, failure to detect a strong (e.g., with signal power greaterthan a threshold) downlink transmit beam, a failure to accurately (e.g.,based on a signal strength threshold) measure the path loss of areference signal, or the like. The recovery process may include the UEperforming a random access procedure (e.g., as illustrated in FIGS. 5Aand 5B) to request a new beam assignment. Specifically, the UE mayindicate a new SSB or CSI-RS for a new transmit beam during the randomaccess procedure. The base station assigns a new beam based on the beamfailure recovery request from the UE by transmitting a downlinkassignment or uplink grant on the PDCCH. Subsequently, a new beam pair(i.e., transmit/receive beam pair) can be established.

Performing a path loss estimation or spatial transmit beam determination(also referred to as spatial transmit QCL determination) on a downlinkreference signal from a neighboring (non-serving) cell may be adifficult task since the neighboring cell may be far away. The path lossestimate is prone to errors, and as a result, the transmit power orspatial transmit determination made by the UE may be prone to errors. Assuch, there are various issues that need to be addressed, such as howthe UE should inform the location server (e.g., location server 230, LMF270) that the path loss reference signal or spatial transmit beamreference signal is failing, how the UE should transmit the uplinkreference signal resources while the downlink reference signals arefailing, and the procedure to avoid the failure of the path loss orspatial transmit estimation for neighboring cells.

When the UE is configured to perform path loss estimation or a spatialtransmit QCL determination using a downlink reference signal from aneighboring cell, and the UE identifies that the reference signal cannotbe used for this purpose, there are several options as to how the UE caninform the location server that the reference signal is failing. As afirst option, the UE can inform the serving base station (which theninforms the location server) through, for example, RRC signaling, or theUE can inform the location server directly through higher layersignaling (e.g., LTE positioning protocol (LPP)) that the path lossdownlink reference signal or spatial transmit QCL downlink referencesignal for a specific uplink reference signal resource is failing. As asecond option, the UE can request to be configured with an alternativeand/or a secondary downlink reference signal from the serving cell toreplace the affected uplink reference signal resource(s). As a thirdoption, the UE can request to be configured with an alternative and/or asecondary downlink reference signal from the neighboring cell(s) toreplace the affected uplink reference signal resource(s).

Being configured with an alternative downlink reference signal meansthat the UE may have been configured with multiple downlink referencesignals and may choose one of them. Being configured with a secondarydownlink reference signal means that the UE is configured with a primarydownlink reference signal, but can use the secondary downlink referencesignal if the primary downlink reference signal fails. The first threeoptions are complementary, insofar as the UE may report that thedownlink reference signal has failed (first option) and request areplacement (second and third options).

As a fourth option, the UE can start a random access procedure with theserving cell, as in the case of a beam failure recovery procedure, butwith a preamble sequence number that indicates that the neighboringcell's downlink transmit beam has failed, rather than a downlinktransmit beam from the serving cell. Based on the sequence number, theserving cell can then inform the location server or the neighboringcell(s) through a higher layer protocol (e.g., the Xn interface) of thebeam failure. As a fifth option, the UE can start a partial beam failurerecovery procedure, meaning that the UE may report that a subset (morethan one) of the neighboring downlink reference signals has failed. Thisreport may be through the regular PUCCH/PUSCH channel, rather than thePRACH, as in the fourth option. The serving cell can then inform thelocation server or the neighboring cell(s) of the failure through ahigher layer protocol (e.g., the Xn interface).

Another issue is how the UE should transmit the uplink reference signalresources while the downlink reference signals are failing. When the UEis configured to perform path loss estimation using a downlink referencesignal from a neighboring cell, and the UE identifies that the referencesignal cannot be used for this purpose, there are various options the UEcan follow. If the downlink reference signal is being used for a pathloss reference, then as a first option, the UE can transmit the uplinkreference signal at its maximum transmit power until a new downlinkreference signal is configured for path loss estimation. The UE maytransmit at its maximum transmit power under the assumption that if itcan no longer detect the downlink reference signal from the neighboringcell, it is because the neighboring cell is far away. As a secondoption, the UE can use a configured secondary downlink reference signal(as requested above) from the serving cell or a neighboring cell toassist with the path loss estimation. As a third option, the UE can usethe path loss downlink reference signal configured for the uplinkreference signal of the serving cell (or of the PUSCH/PUCCH). As afourth option, the UE can use a default downlink transmit beam (i.e.,the same downlink transmit beam) for both the path loss reference signaland the spatial QCL reference signal. For example, the UE could use thetransmit beam with the lowest uplink reference signal resource ID.

If the downlink reference signal is being used for a spatial QCLreference, then as a first option, the UE can use a configured secondarydownlink reference signal from the serving cell to assist with thederivation of the uplink transmit beam (spatial QCL). As a secondoption, if the UE has been configured with multiple downlink referencesignals from a specific neighboring cell, the UE can transmit theeffected resource with one of the uplink transmit beams derived from theother downlink reference signals of the same neighboring cell. As athird option, if the UE has only been configured with one downlinkreference signal from the neighboring cell, the UE can transmit theeffected resource with an uplink transmit beam derived from a downlinkreference signal of the serving cell. As a fourth option, the UE can usea default downlink transmit beam (i.e., the same downlink transmit beam)for both the path loss downlink reference signal and the spatial QCLdownlink reference signal. For example, the UE could use the transmitbeam with the lowest uplink reference signal resource ID.

As will be appreciated, other than using the maximum transmit power inthe case of a failed downlink reference signal being used for a pathloss reference, the options for both path loss and spatial QCL uplinkreference signals are similar.

Referring now to the procedure to avoid the failure of the pathloss/spatial transmit QCL estimation downlink reference signals fromneighboring cells, there are several steps that can be taken. First, thelocation server can configure the UE with downlink reference signalsfrom neighboring cells to perform the path loss or spatial transmit beamdetermination. Second, the UE can periodically report the RSRP, RSRQ,and/or SINR of any downlink reference signals from neighboring cellsthat are being used for path loss or spatial transmit QCL estimation ofuplink reference signal transmissions. Alternatively, the locationserver can configure for which downlink reference signals such reportingwould be helpful. This may be accomplished through direct reporting tothe location server or reporting to the base station, which then relaysthe report to either neighboring base stations (e.g., via the Xninterface) or to the location server (e.g., location server 230, LMF270). Third, when the RSRP/RSRQ/SINR is low, the location server canproactively reconfigure the downlink reference signals.

An RSRP/RSRQ/SINR threshold can be used to decide whether the currentdownlink reference signal can be used for path loss reference estimationor spatial QCL determination.

FIG. 8 illustrates an exemplary method 800 of wireless communication,according to aspects of the disclosure. In an aspect, the method 800 maybe performed by a UE (e.g., any of the UEs described herein).

At 810, the UE receives a positioning configuration (e.g., via RRC, LPP,and/or other signaling from a location server, serving cell, or othersuch entity), the positioning configuration including at least anidentifier of a first downlink reference signal from a neighboring cellto be used for estimating a downlink path loss or determining an uplinkspatial transmit beam. In an aspect, operation 810 may be performed byWWAN transceiver 310, processing system 332, memory component 340,and/or positioning component 342, and or all of which may be consideredmeans for performing this operation.

At 820, the UE determines whether or not the first downlink referencesignal received from the neighboring cell has failed. In an aspect,operation 820 may be performed by WWAN transceiver 310, processingsystem 332, memory component 340, and/or positioning component 342, andor all of which may be considered means for performing this operation.

At 830, in response to determining that the first downlink referencesignal has failed, the UE estimates the downlink path loss or determinesthe uplink spatial transmit beam based on a second downlink referencesignal received from the neighboring cell or a serving cell for the UE.In an aspect, operation 830 may be performed by WWAN transceiver 310,processing system 332, memory component 340, and/or positioningcomponent 342, and or all of which may be considered means forperforming this operation.

At 840, the UE transmits an uplink reference signal for positioningbased on the estimated downlink path loss, the determined uplink spatialtransmit beam, or a combination thereof. In an aspect, operation 840 maybe performed by WWAN transceiver 310, processing system 332, memorycomponent 340, and/or positioning component 342, and or all of which maybe considered means for performing this operation.

FIG. 9 illustrates an exemplary method 900 of wireless communication,according to aspects of the disclosure. In an aspect, method 900 may beperformed by a location server (e.g., location server 230, LMF 270).

At 910, the location server configures (e.g., via LPP) a UE (e.g., anyof the UEs described herein) to receive at least a first downlinkreference signal from a neighboring cell to be used to estimate adownlink path loss or determine an uplink spatial transmit beam. In anaspect, operation 910 may be performed by network interface(s) 390,processing system 394, memory component 396, and/or positioningcomponent 398, and or all of which may be considered means forperforming this operation.

At 920, the location server receives, from the UE, a report indicating asignal quality of the first downlink reference signal. In an aspect,operation 920 may be performed by network interface(s) 390, processingsystem 394, memory component 396, and/or positioning component 398, andor all of which may be considered means for performing this operation.

At 930, based on the signal quality of the first downlink referencesignal being below a threshold, the location server configures the UE toreceive at least a second downlink reference signal from the neighboringcell or a serving cell to be used to estimate the downlink path loss ordetermine the uplink spatial transmit beam. In an aspect, operation 930may be performed by network interface(s) 390, processing system 394,memory component 396, and/or positioning component 398, and or all ofwhich may be considered means for performing this operation.

FIG. 10 illustrates an exemplary method 1000 of wireless communication,according to aspects of the disclosure. In an aspect, the method 1000may be performed by a UE (e.g., any of the UEs described herein).

At 1010, the UE receives, from a network node (e.g., a serving basestation or a location server), a configuration (e.g., via RRC, LPP,and/or other signaling from a location server, serving cell, or othersuch entity) to use at least a first downlink reference signal from aneighboring cell to estimate downlink path loss or determine an uplinkspatial transmit beam. In an aspect, operation 1010 may be performed byWWAN transceiver 310, processing system 332, memory component 340,and/or positioning component 342, and or all of which may be consideredmeans for performing this operation.

At 1020, the UE sends, to the network node, a report indicating a signalquality of the first downlink reference signal. In an aspect, operation1020 may be performed by WWAN transceiver 310, processing system 332,memory component 340, and/or positioning component 342, and or all ofwhich may be considered means for performing this operation.

At 1030, based on the signal quality of the first downlink referencesignal being below a threshold, the UE receives, from the network node,a configuration (e.g., via RRC, LPP, and/or other signaling from alocation server, serving cell, or other such entity) to use at least asecond downlink reference signal from the neighboring cell or a servingcell to estimate the downlink path loss or determine the uplink spatialtransmit beam. In an aspect, operation 1030 may be performed by WWANtransceiver 310, processing system 332, memory component 340, and/orpositioning component 342, and or all of which may be considered meansfor performing this operation.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implemented orperformed with a general purpose processor, a DSP, an ASIC, an FPGA, orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general purpose processor maybe a microprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), registers, hard disk, aremovable disk, a CD-ROM, or any other form of storage medium known inthe art. An exemplary storage medium is coupled to the processor suchthat the processor can read information from, and write information to,the storage medium. In the alternative, the storage medium may beintegral to the processor. The processor and the storage medium mayreside in an ASIC. The ASIC may reside in a user terminal (e.g., UE). Inthe alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

In one or more exemplary aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and Blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of thedisclosure, it should be noted that various changes and modificationscould be made herein without departing from the scope of the disclosureas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the aspects of the disclosuredescribed herein need not be performed in any particular order.Furthermore, although elements of the disclosure may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method of wireless communication performed by auser equipment (UE), comprising: receiving a positioning configuration,the positioning configuration including at least an identifier of afirst downlink reference signal from a neighboring cell to be used forestimating a downlink path loss; determining that the first downlinkreference signal received from the neighboring cell cannot be used forestimating the downlink path loss; in response to the determination,estimating the downlink path loss based on a second downlink referencesignal received from the neighboring cell or a serving cell; andtransmitting an uplink reference signal for positioning having atransmit power set based on the estimated downlink path loss.
 2. Themethod of claim 1, wherein the second downlink reference signal is asynchronization signal (SS)/physical broadcast channel (PBCH) block fromthe serving cell that the UE uses to obtain a master information block(MIB) for the serving cell.
 3. The method of claim 1, furthercomprising: setting a spatial beam direction for a transmit beamdirected to the neighboring cell, the transmit beam carrying the uplinkreference signal.
 4. The method of claim 1, further comprising:reporting, to the serving cell or a location server, that the firstdownlink reference signal has failed based on determining that the firstdownlink reference signal cannot be used for estimating the downlinkpath loss.
 5. The method of claim 1, wherein the UE determines that thefirst downlink reference signal cannot be used for estimating thedownlink path loss based on the signal quality of the first downlinkreference signal being below a threshold.
 6. The method of claim 5,wherein the threshold comprises a reference signal received power (RSRP)threshold configured to the UE.
 7. The method of claim 1, furthercomprising: transmitting, to the serving cell via a physical randomaccess channel (PRACH) procedure, a sequence number indicating that thefirst downlink reference signal has failed based on determining that thefirst downlink reference signal cannot be used for estimating thedownlink path loss.
 8. The method of claim 1, further comprising:requesting that the serving cell transmit an alternative and/orsecondary downlink reference signal configured to enable the UE toestimate the downlink path loss.
 9. The method of claim 1, furthercomprising: requesting that the neighboring cell transmit an alternativeand/or secondary downlink reference signal configured to enable the UEto estimate the downlink path loss.
 10. The method of claim 9, whereinthe request is sent to the serving cell.
 11. The method of claim 1,further comprising: initiating a partial beam failure recovery procedureto report that a subset of downlink reference signals from theneighboring cell have failed.
 12. The method of claim 11, wherein thesubset of downlink reference signals comprises more than one downlinkreference signal from the neighboring cell.
 13. The method of claim 1,wherein a plurality of downlink reference signals is received from theneighboring cell, and wherein the first and second downlink referencesignals are two of the plurality of downlink reference signals.
 14. Themethod of claim 13, wherein: the first downlink reference signal isconfigured for downlink path loss estimation for a first carrierbandwidth part used to communicate with the neighboring cell, and thesecond downlink reference signal is configured for downlink path lossestimation for a second carrier bandwidth part used to communicate withthe neighboring cell.
 15. The method of claim 1, wherein: the firstdownlink reference signal is the only downlink reference signal the UEreceives from the neighboring cell, and the second downlink referencesignal is a downlink reference signal received from the serving cell.16. The method of claim 1, wherein the second downlink reference signalis a default downlink reference signal used for the estimated downlinkpath loss.
 17. The method of claim 16, wherein the second downlinkreference signal is received on a transmit beam from the serving cell.18. The method of claim 1, further comprising: transmitting uplinkreference signals at a maximum transmit power after determining that thefirst downlink reference signal cannot be used for estimating thedownlink path loss and before estimating the downlink path loss based onthe second downlink reference signal.
 19. The method of claim 1, whereinthe second downlink reference signal is a secondary downlink referencesignal from the serving cell.
 20. The method of claim 1, wherein thesecond downlink reference signal is a synchronization signal(SS)/physical broadcast channel (PBCH) block from the serving cell thatthe UE uses to obtain a master information block (MIB) for the servingcell.
 21. A user equipment (UE), comprising: a memory; at least onetransceiver; and at least one processor communicatively coupled to thememory and the at least one transceiver, the at least one processorconfigured to: receive, via the at least one transceiver, a positioningconfiguration, the positioning configuration including at least anidentifier of a first downlink reference signal from a neighboring cellto be used for estimating a downlink path loss; determine that the firstdownlink reference signal received from the neighboring cell cannot beused for estimating the downlink path loss; estimate, in response to thedetermination, the downlink path loss based on a second downlinkreference signal received from the neighboring cell or a serving cell;and transmit, via the at least one transceiver, an uplink referencesignal for positioning having a transmit power set based on theestimated downlink path loss.
 22. The UE of claim 21, wherein the seconddownlink reference signal is a synchronization signal (SS)/physicalbroadcast channel (PBCH) block from the serving cell that the UE uses toobtain a master information block (MIB) for the serving cell.
 23. The UEof claim 21, wherein the at least one processor is further configuredto: set a spatial beam direction for a transmit beam directed to theneighboring cell, the transmit beam carrying the uplink referencesignal.
 24. The UE of claim 21, wherein the at least one processor isfurther configured to: report, via the at least one transceiver, to theserving cell or a location server, that the first downlink referencesignal has failed based on determining that the first downlink referencesignal cannot be used for estimating the downlink path loss.
 25. The UEof claim 21, wherein the UE determines that the first downlink referencesignal cannot be used for estimating the downlink path loss based on thesignal quality of the first downlink reference signal being below athreshold.
 26. The UE of claim 25, wherein the threshold comprises areference signal received power (RSRP) threshold configured to the UE.27. The UE of claim 21, wherein the at least one processor is furtherconfigured to: transmit, via the at least one transceiver, to theserving cell via a physical random access channel (PRACH) procedure, asequence number indicating that the first downlink reference signal hasfailed based on determining that the first downlink reference signalcannot be used for estimating the downlink path loss.
 28. The UE ofclaim 21, wherein the at least one processor is further configured to:request that the serving cell transmit an alternative and/or secondarydownlink reference signal configured to enable the UE to estimate thedownlink path loss.
 29. The UE of claim 21, wherein the at least oneprocessor is further configured to: request that the neighboring celltransmit an alternative and/or secondary downlink reference signalconfigured to enable the UE to estimate the downlink path loss.
 30. TheUE of claim 29, wherein the request is sent to the serving cell.
 31. TheUE of claim 21, wherein the at least one processor is further configuredto: initiate a partial beam failure recovery procedure to report that asubset of downlink reference signals from the neighboring cell havefailed.
 32. The UE of claim 31, wherein the subset of downlink referencesignals comprises more than one downlink reference signal from theneighboring cell.
 33. The UE of claim 21, wherein a plurality ofdownlink reference signals is received from the neighboring cell, andwherein the first and second downlink reference signals are two of theplurality of downlink reference signals.
 34. The UE of claim 33,wherein: the first downlink reference signal is configured for downlinkpath loss estimation for a first carrier bandwidth part used tocommunicate with the neighboring cell, and the second downlink referencesignal is configured for downlink path loss estimation for a secondcarrier bandwidth part used to communicate with the neighboring cell.35. The UE of claim 21, wherein: the first downlink reference signal isthe only downlink reference signal the UE receives from the neighboringcell, and the second downlink reference signal is a downlink referencesignal received from the serving cell.
 36. The UE of claim 21, whereinthe second downlink reference signal is a default downlink referencesignal used for the estimated downlink path loss.
 37. The UE of claim36, wherein the second downlink reference signal is received on atransmit beam from the serving cell.
 38. The UE of claim 21, wherein theat least one processor is further configured to: transmit, via the atleast one transceiver, uplink reference signals at a maximum transmitpower after determining that the first downlink reference signal cannotbe used for estimating the downlink path loss and before estimating thedownlink path loss based on the second downlink reference signal. 39.The UE of claim 21, wherein the second downlink reference signal is asecondary downlink reference signal from the serving cell.
 40. The UE ofclaim 21, wherein the second downlink reference signal is asynchronization signal (SS)/physical broadcast channel (PBCH) block fromthe serving cell that the UE uses to obtain a master information block(MIB) for the serving cell.
 41. A user equipment (UE), comprising: meansfor receiving a positioning configuration, the positioning configurationincluding at least an identifier of a first downlink reference signalfrom a neighboring cell to be used for estimating a downlink path loss;means for determining that the first downlink reference signal receivedfrom the neighboring cell cannot be used for estimating the downlinkpath loss; means for estimating the downlink path loss based on a seconddownlink reference signal received from the neighboring cell or aserving cell; and means for transmitting an uplink reference signal forpositioning having a transmit power set based on the estimated downlinkpath loss.
 42. A non-transitory computer-readable medium storingcomputer-executable instructions that, when executed by a user equipment(UE), cause the UE to: receive a positioning configuration, thepositioning configuration including at least an identifier of a firstdownlink reference signal from a neighboring cell to be used forestimating a downlink path loss; determine that the first downlinkreference signal received from the neighboring cell cannot be used forestimating the downlink path loss; estimate the downlink path loss basedon a second downlink reference signal received from the neighboring cellor a serving cell; and transmit an uplink reference signal forpositioning having a transmit power set based on the estimated downlinkpath loss.